SS 1 BIOLOGY.

TUESDAY 08/09/2020

CORRECTION TO LAST TUESDAY CLASS ACTIVITY

1. The purple colour of potassium permanganesecrystal gradually spread throughout the water in the glass jar because molecules of solute move from higher concentration to the region of low concentration until solution is uniform b)This process/ phenomenon is called Diffusion.
2. Two factors that will increase the rate of diffusion are:increase in the temperature of the solution , size of the solute and stirring or shaking of the solution.
3. In Volvox, each cell is connected to other cells to form a colony of cells shaped like a hollow sphere. In spirogyra, cells are connected to one another end to end to form filament.
4. Functions of the following organelles: a) Rough endoplasmic recticulum: it aids in transportation of materials within the cytoplasm b)Ribosome:it is the site for protein synthesis c)Mitochondrion: it is the power house of the cell. It is the site for energy production. d) Golgi apparatus: They in synthesis, packaging and distribution of materials. e) Centrioles: They are important in cell division.

CORRECTION TO WEDNESDAY CLASS ACTIVITY

1. a)Kingdom Fungi                                                                                                                                                                            b)Because :i.it lacks chlorophyll    ii.it stores excess food as glycogen    iii. The cell wall is made of chitin instead of cellulose in plants                                                                                                                           c)other four organisms in kingdom fungi are: i.Bread mould/mucor    ii.yeast          iii. Toadstool         iv. Rhizopus.
2. a)Phylum Mollusca                b)Reasons: i.it has a large flattened  muscular  foot for movement       ii.it has tentacles that bear eyes.          Iii.it has a coiled calcereous shell.         Iv.it has soft unsegmented body.                  d)its mode of nutrition is Saprophytic nutrition               e)economic important of snail: i. source of protein          ii.source of income  for the farmers         iii.its shell serves as source of calcium in animal feed

TUESDAY   01/09/2020

CLASS ACTIVITY

1. a) Using the idea of concentration gradient, explain why the purple colour gradually spreads throughout the water in the jar, when potassium permanganate crystal is dropped into a gas jar of water.                                                                                                                                                                                       b) Name the biological phenomenon that occurred in the process above.      
2. c) State 2 factors that will increase the rate of the phenomenon.
3. How is the organization in the spirogyra different from that of volvox
4. State the functions of the following organelles: rough endoplasmic reticulum, ribosome, mitochondrion, golgi apparatus, centriole and smooth endoplasmic reticulum.

WEDNESDAY    02/09/2020

CLASS ACTIVITY

1. a) Name the kingdom to which mushroom belongs.                                                                                      
2.   b) State three reasons for your answer in (ia) above.                                                                                                                  
3.   c)Mention other four organisms that belong to the kingdom above.

d)State two economic importance of mushroom.

• Name the phylum to which Africa giant snail belongs.                                                                                                                  
• b) State three reasons for your answer in (2a) above.                                                                                                                        
•  c)Explain briefly the role of Africa giant snail in nutrient cycling.

d) What is the mode of nutrition of the organism above.

e) State two economic importance of this organism.

25/08/2020

CLASS ACTIVITY

1. Mention three adaptive features each of animals and plants in desert land.
2. Mention three adaptive features of animals in the hot desert in order to regulate temperature.
3. Highlight two adaptive features of animals in the cold desert in order to regulate temperature.
4. Explain  how the kidney tubules in the kangaroo rat enable it to stay without water for long period of time.
5. Define xerophytic and pyrophytic plants.

TUESDAY 18/08/2020

CORRECTION TO WEDNESDAY CLASS ACTIVITY

1. The spirogyra carries out sexual reproduction by conjugation in which two filaments come together. The male gamete from one filament moves to the other filament and fuses with the female gamete
2. Mitosis is important for the growth of an organism. In some organisms,. It  is important for the repair of worn out tissues of an organism. In some organisms, mitosis is important for sexual reproduction, e.g in flowering plants that reproduce asexually..
3. The paramecium has cilia which are fine, hair-like structures that move in a rhythmic and co-ordinated way so that the organism can move from one place to another. The Euglena has a long, whip-like flagellum  which moves in awave-like manner to enable the cell to move in water.
4. Stages in mitosis—In prophase stage, the chromosomes condense  and are visible under microscope. In the late prophase,, spndle fibres are formed and the nuclaer envelop disappears. During metaphase,  chromosomes consisting of sister chromatids line up at the equator of the spindle. During anaphase,  chromatids are pulled apart to opposite poles of the cell. During telophase, the spindle fibres break down. The nuclear envelop and nucleolus reform.  Two daughter cells with the same number of chromosomes as the parent cell are formed.

CORRECTION TO TUESDAY ACTIVITY

1. Respiration releases energy, which is required by the living organisms to carry out the life processes.
2. Aerobic respiration occurs in the presence of oxygen and releases a large amount of energy. Anaerobic respiration occurs in the absence of oxygen and releases a small  amount of energy.
3. Crossing over occurs at this stage.
4. Reduction division is important in organisms that undergo sexual reproduction in order to maintain the chromosome number of the species that is produced. It is necessary to produce haploid cell, so that one haploid cell from male and one from female fuses together to form diploid zygote cell.
5. Meiosis produces haploid gametes and this allow for the diploid number of chromosomes to be maintained when male and female gametes fuse. Meiosis also increase variation in the gametes produced. This increases the chances of survival during changes in the environment.

12/08/2020

WEDNESDAY      

1. How does the spirogyra carry out sexual reproduction?
2. Explain the importance of mitosis in the life of a  mammal
3. Name and describe the structures that aid the paramecium and the euglena in locomotion.
4. Describe the stages in mitosis

11/08/2020 TUESDAY.

TUESDAY   

CLASS ACTIVITY.

1. What is the importance of respiration to living organisms?
2. How does aerobic respiration differs from anaerobic respiration?
3. What occurs in  meiosis prophase 1?
4. Why is reduction division important in organisms that undergo sexual reproduction.
5. State the importance of meiosis in the life of animals.

WEDNESDAY CORRECTION

1. Strata.
2. i) Flying squirrel: it possesses muscular membrane along sides of its body that enable  it to glide from tree to tree     ii)Tree  frog : it has toes with stick  pads that help it to grasp onto the tree branches       iii) gecko: it has friction pads on their feet to help them climb up the smooth  tree barks.
3. How plants and animals in savanna  are adapted to the environment conditions: Savana experiences wet and dry season. During the dry season, water is scarce. Therefore many birds and some nomadic animals  such as zebra ,buffalo migrate to regions  of plenty water .Their hoofed feet allow them to travel great distances. Some animals like elephant deal with annual water shortage by tearing  away bark  of baobab trees to get water found in the trunk. Some animals remain  dormant in their burrows during dry season.                                                              The challenges that grassland plants face during the dry season are shortage of water and occurrence of  fires. Some savanna plants  such as baobab are fire and drought resistance. Baobab has a very large trunk to store water during the dry season and  the succulent bark also  contains resins  that protect  the tree from bush  fires.

i.) Cactus: it has succulent stem that stores water. It has tiny, needle-like or spiny leaves to reduce rate of transpiration.                                                                                                                           

ii) Baobab: it has large or bottle-shaped massive  trunk that store water. It has deciduous leaves  to prevent transpiration during dry season.                                                                                                      iii)Kangaroo rat: it  can survive without drinking water. It derives moisture from the food it eats.     iv) Acacia: it has deep taproot to absorb water during the dry season. It has small leaves to prevent water loss/transpiration

WEDNESDAY     05/08/2020

CLASS ACTIVITY

1. What is another name for different layers of a tropical rainfall?
2. Animals in rainforest have adaptations to help them move about. Describe the adaptation for each of the following organisms;  i) flying squirrel  ii) tree frog     iii) gecko
3. Explain how plants and animals have adapted to the environmental conditions in a savanna?
4. Mentionthe habitat and 2 adaptive features of these organisms: cactus, baobab, kangaroo rat and acacia

TOPIC: GRASSLAND/ SAVANNA HABITAT

A  grassland is a plant community in which grass species are dominant with short but scattered trees and shrubs.The grassland lies between  the forest and the desert/arid land. The rainfall in grasslands is only sufficient to support the growth of grasses. Plants and animals  have to adapt to changing conditions during the dry and wet seasons

 Types of Grassland

There are 2 major types:  i) Tropical grassland    ii) Temperate grassland

Characteristics of Grassland

1. Predominance of grass
2. Presence of short but scattered trees
3. Absence of stratified layer/canopy
4. Presence of fire resistant trees
5. Presence of drought resistant trees
6. Presence  of deciduous plants

   ARID LAND OR DESERT HABITAT

Arid lands/ deserts refer to areas of very low rainfall and high evaporation rate. Arid lands are the driest habitat, receiving less than 25cm of annual rainfall.

Types of Arid land

1. Hot desert               ii)Cold desert

CLASS ACTIVITY

1. Write 3 differences between hot and cold desert
2. Mention 4 factors affecting the arid land

3. What are deciduous plants?

4/08/2020 TUESDAY

CORRECTION TO LAST TUESDAY ACTIVITY

1. Organism in Brackish habitat—Crab,–it furrows into the mud against predators, strong wave or tides                                                                                                                                                                          Organism in Brackish habitat—-Mosquito larvae/pupa,—possession  of breathing  tube/trumpet for gaseous exchange.                                                                                                                                        b) In  fresh water habitat—Spirogyra—it has mucilagenous cover, which protects it  in water.

Estuarine habitat	Fresh water habitat
Presence of salt water	Absence of salt water
High level of nutrients	Low level of nutrients
Low concentration of oxygen	High concentration of oxygen

28/ 07/2020 TUESDAY

CORRECTION TO WEDNESDAY ACTIVITY

1. Tropism/. tropic movement:This is growth movement of plant part in response to an external unilateral stimulus and it is directl y dependent on the direction of the stimulus. Eg phototropism,, geotropism, hydrotropism

Nastism/nastic movement: this refers to the non-directional response of an organism to stimuli like touch, temperature, humidity. Eg Mimosa plant to touch.

Taxism/taxic movement: this refers to the tendency of an organism to move away or towards a stimulus. Examples are phottaxis, thermotaxis, and hydrotaxis

Tropism	Nastism
Response leads to growth	It does not
Response is slow	Response is fast
Response is towards the direction of the stimulus	Response is not towards the direction of the stimulus
Movement is not easily reversed	Movement is reversible

2. Stages oif mitosis: prophase, metaphase, anaphase and telophase

3.Differences btw mitosis and meiosis

mitosis	meiosis
Daughter cells contain same number of chromosome as the parent cell ie diploid	Daughter contain half number of the chromosomes as the parent cell ie haploid
Pairing of homologous chromosomes does not occur	Homologous chromosomes pair at prophase 1
No crossing over 	Crossing over occurs
Daughter cells are identical to parent cell. Two daughter cells are produced from one parent cell	Variationoccurs i9n the daughter cells Four daughter cells are produced
It occurs in soma body c ell during growth or repair of body parts	Occurs in the gonads during gamete formation.

The point of crossing over is called Chiasmata

5. A chromosome is a two identical sister chromatids which has become coiled and shortened

Chromatin is a long thin thread found in the nucleus

Chromatids are two sister chromatins which are joinned at the centromere formed from replication of chromatin thread

TUESDAY  28/07/2020

Hello students, hope you are still updating yourselves on the corrections to the class activities.

TOPIC: ESTUARINE /BRACKISH HABITAT.

An estuarine habitat is a body formed at the coastal as a result of action of tides which mix salt water from sea with fresh water from land. It is a body of water located between a fresh water environment and a salt water environment.

Characteritics of  Brackish Habitat

1. Fluctuation in Salinity: Salinity is lower at  mouth of the river and gets higher towards the sea.
2. Turbidity:Turbidity increases  during the rain season when a lot of debis are brought into the river.
3. Shallownes of water: The water in estuarine is very shallow.
4. High Level of Nutrients; It contains a lot of nutrients due to presence of organic detritus
5. Low oxygen content:Oxygen content is low, therefore, lot of microbial activities are carried out anaerobically.

Types of Eutuarine

1. Delta
2. Lagoon
3. Bay

FRESH WATER HABITAT

Fresh water habitat is abody of water  formed  mainly from in water and contains very low level of salinity. Examples are pond, stream, river  and stream.

Charateritics of Fresh water habitat

1. Low salinity
2. Small in size
3. Variation in temperature
4. High concentration of oxygen
5. Shallowness of the River
6. Seasonal variation

CLASS ACTIVITY

1. Mention one organism in Brackish and Freshwater habitats and one adaptive feature each
2. Highlight two differences between estuarine and fresh water habitats

WEDNESDAY 29/07/2020

TOPIC: TERRESTRIAL ENVIRONMENT

Terrestrial environment refers to the land environment.

Types of Terrestrial Environment:

1. Marshes
2. Forest
3. Grassland
4. Arid land

MARSHES

Marshes are low-lying wetlands covered under shallow water for long period of time. They are usually formed in lowland  and plains near lakes. Marshes are wetlands with grass-like vegetation that grows in waterlogged soil.

Characteristics of Marshes

1. Low land habitat
2. Nature of the soil is  usually wet, soft, water-logged and poorly aerated.
3. High flooding
4. Presence of stagnant water
5. Presence of organic matter
6. High rate of organic decomposition
7. High relative humidity

FORESTLAND

A Forest is an extensive  community of plants dominated by tall trees. Forest are largely made up of woody trees. There different types of forests: Tropical rain forest and Temperate rain forest.

Characteristics of Tropical rain forest:

1. Presence of broad leaves
2. Presence of buttress roots
3. Presence of tall forest
4. Existence of canopies
5. Trees exist in layers/ storeys
6. Presence of epiphytes

Strata in the Forestland

Due to the dense growth of the branches and leaves of tall trees, sunlight is not able to penetrate through the thick foliage to the shorter trees. The tropical rainforest can be divided into five strata/layer;

1. Emergent/Upper layer; They are the tallest trees over 40m tall.The crown of the emergent do not touch each other. Examples include iroko, obeche, ebony, Africa walnut etc
2. Canopy/ Middle layer: It is the second layer of the rainforest.It is made up of tall trees of about 16-40m.Their crown(branches) touches each other and forming a continuous canopy just below the emergent, this reduces the amount of sunlight  can that penetrate. There are presence of epiphytes in this layer.
3. Understorey/Lower layer; This the third layer, which is made up small trees, less than  16m tall. They also form continuous canopy below the middle layer.
4. The Shrub layer: This layer is made nup of small trees between 1-5min height
5. The Ground/Forest layer: This contains wet and shade- loving plants which grow on the floor of the forest.The bplants hardly receive sunlight due to canopies formed by bigger plants The forest floor is  dark and humid. Examples of plants are bryophytes eg mosses, liverwort, lichen,and ferns.

CLASS ACTIVITY

1. Define relative humudity
2. Mention two effects of high relative humudity on the ecosystem.

WEDNESDAY 22/07/2020

CLASS ACTIVITY

1. Explain the differences between taxism, nastism and tropism. Hence, give two examples each of of these movement
2. State the main stages of mitosis
3. Mention four differences between mitosis and meiosis
4. Study the diagram below and answer the questions that follow: a)What is the name of the point where crossing over occurs? b)Mention two importance of the crossing over in living organisms. c) Differentiate between chromosome, chromatid and chromatin

TUESDAY     21/07/2020

TOPIC: AQUATIC  HABITATS.

Aquatic habitat is a body of water in which certain organisms live naturally.  Organisms that live in water are referred to as Aquatic organisms.

Types of Aquatic Habitats

1. Marine habitat
2. Estuarine habitat
3. Freshwater habitat

Marine habitats are habitats which consists of salt water. They consist of ocean and seas and their shore.

Characteristics of a Marine habitats:

1. High salinity
2. High density
3. Water pressure increases with dept
4. Oxgyen concentration highest at the surface  while it decreases  with depth.
5. Light penetration : Light penetrates at upper layer. Penetration of light depends on turbidity
6. High pH: Salt water is known  to be alkaline about 8.0-9.0 near the surface.
7. The movement of ocean water results into tides, current and waves.

Major Zones of Marine Habitat                                                                                                                         

The  major ecological zones of the marine habitats include:

1. Supratidal or Splash zone: This is the exposed zone of marine habitat. It is the area where

water  splashes when the waves  break at the shore.

• Intertidal/Neritic zone; This is a zone that is only exposed when the tide is low and covered by water at high tide.It has high photosynthetic activities because of the aboundant sunlight. The temperature and the salinity of this zone fluctuate.
• Subtidal/Litoral Zone:This zone is about 200m deep. It is submerged in water most of the time and exposed to air only during extremely  low tides for short periods of time. The temperature and the salinity do not fluctuate. It also has abundant of sunlight  and nutrients.
• Pelagic Zone: This zone is also under water and is about 500m deep. It has low light penetration and low nutrients.
• Benthic Zone; This zone is about 7000m deep. It has low penetration of light , low temperature, high pressure, low photosynthetic activities and the primary production of food is by chemosynthesis.
• Hadal /Aphotic Zone: This is the deepest zone of marine habitat. It is over 7000m deep. It forms the floor of the  ocean. There is no light penetration , hence on photosynthetic activities.

On the basis of depth or light penetration, there  exist three zones which are;

1. Euphotic zone: This is area where there is enough light penetration for photosynthesis to take place.
2. Diphotic zone: This is a zone where there is dim light. The intensity of light is too low for photosynthesis to take place. Although, producers and consumers are found here.
3. Aphotic zone: This refers to the sea floor/bottom. It is characterized by cold dark water without light penetration and very few organisms are  found here.

Organisms in the Marine Habitats include: crab, star fish, plankton, slug, cray fish, tilapia fish etc

CLASS ACTIVITY

1. Highlight two adaptive features of these organisms to marine habitat; Tilapia fish, star fish, crabs and sea weeds

2. Construct a food chain in marine habitat involving four trophic levels

3. State two differences between pelagic and benthic zone. Hence ,what are benthos?

17/07/2020

CORRECTION TO TUESDAY CLASS ACTIVITY

1. The reason is that the bacteria may not be completely killed by the antibiotic and there is possibility of acquiring a resistance to the antibiotic.

2. Fermentation is the chemical breakdown of substances like glucose anaerobically by the action of microorganisms like bacteria.

3. Tanning is the process of making leather from hide of animals. This is done by treating hide with microorganisms.

WEDNESDAY

1. Immunization /Vaccination is the administration of vaccines to protect people from diseases.
2. How vaccination protect the body: Vaccines are dead or attenuated(weakened )viruses or bacteria that act on antigens /germs. Because they are weakened, they are unable to cause the diseases. When vaccines are introduced into the body, the immune system reacts or respond by producing antibodies and this enables a person to develop immunity without getting the disease. These antibodies are registered in the immune system, in case the life germ enters the body, it can quickly produce more of the registered anti bodies and protect the body against the disease

WEDNSEDAY, 15/07/2020

SUB-TOPIC: HARMFUL EFFECTS OF MICROORGANISMS

Whilke many microorganisms are beneficial to us, they can also be harmful. Some of the harmful effects include:

1. They cause food spoilage
2. They produce toxin that cause diseases
3. They cause deterioration of materials
4. They can cause diseases
5. They cause reduction in the crop yields
6. They reduce the quality of the products

MODE OF TRANSMISSION OF MICROORGANISMS

The spread of microorganisms from one person to another occur through the air, water, food and physical contact with and infected person or contaminated objects and vectors

CONTROL OF HARMFUL MICROORGANISMS

Harmful microorganisms can controlled in the following ways:

1. High temperature
2. ues of Antibiotics/drugs
3. Preserving food by salting
4. Immunization/Vaccination
5. Sterilization by boiling
6. Quarantine services
7. Promote Health Education
8. Use of Antiseptics
9. Use of Distinfectants
10. Personal Hygiene

CLASS ACTIVITY

1. What is immunization?
2. How does vaccination protect the body /

14/07/2020   TUESDAY

CONCEPT OF CULTURING

Culturing involves the technique of growing microorganisms in the laboratory. It involves the making of sterile medium, inoculating, incubating and examining microorganisms. To identify microorganisms, microbiologists need to culture or grow them in the laboratory. A  culture  is a group of microbial cell that grow on a medium. A growth medium provides nutrients that are required for  microorganisms to grow. Growth media may be liquid medium(Broth) or solid medium(Agar). Microorganisms grow on the surface of the solid medium to form colonies. A colony is a group of identical  cells  that is derived from single cell.

Growth of Microorganisms.

Microbial growth is measured in terms of the increase in the number of cells. A growth curve can be used to describe the growth of microorganisms in environment with limited resources. Microorganisms,  like other living things , do increase in size and multiply in number of cells using either culture medium or any suitable surfaces such as moist bread , exposed  tomato paste as source of food.                            Four stages of growth curve are as follows:

1. Lag phase- Growth is slow at this stage as the microorganisms are adapting to the conditions in the environment.
2. Exponential phase: The microorganisms reproduce rapidly  and their numbers increase exponentially.
3. Stationary phase : Eventually, the nutrients in the environment are exhausted in the medium. Toxic by-products have also accumulated in the medium. At this stage, the net growth is zero and  their number stabilizes.
4. Death phase: In this stage, cell die faster  than they are replaced and microbial population decreases in size rapidly.

MICROORGANISMS  IN  ACTION.            

    Some microorganisms are beneficial to us, some are harmful to us while some are neutral.

Beneficial Effects of Microorganisms:

1. Decomposition: Microorganisms like saprophytic bacteria are decomposers. Decomposers play an important role in the decomposition of dead plants and animals thereby releasing nutrients to the soil.
2. Sewage Treatment: Sewage is normally decomposed by saprophytic bacteria. Bacteria present in the sewage secrete enzymes to digest/ decompose the solid organic matter into soluble, harmless substances.
3. Synthesis of Vitamins: The intestinal bacteria in man can synthesise vitamin K which is responsible for blood clotting. They also synthesise vitamin B.
4. Digestion of the Cellulose: Cellulose bacteria are present in the rumen of ruminant animals and help them to digest cellulose
5. Fermentation Products: These products include: a)Yoghurt making: Yoghurt is made from fermented milk using bacteria like Lactobaccillus spp,and Streptococus spp. b)Cheese making. c) Bread making . d) Production of Alcohol and Vinegar
6. Production of Antibiotics : They are complex substances produced by microorganisms as by-product which they excrete. They are used mainly in the treatment of bacterial disease. Soil bacteria and fungi are the main antibiotic producers . The best antibiotics are Penicillin produced by the fungi Penicillium and Streptomycin and Tetracycline produced by the Streptomyces bacteria.
7. Processing of Raw materials e.g Tanning of leather and Retting of fibre

Class Activity

1. Explain why patients who are treated with antibiotics are always advised to take the complete course treatment, rather than stop the treatment as soon ad they feel better.
2. What is fermentation
3. Explain tanning of leather

WEDNESDAY. 08/07/2020

MODE OF LIFE OF BACTERIA

Bacteria occur in almost every environment. They are found in food, water,soil,in plants and in the body of animals esp. in the intestines. Bacteria may be:

i. Saprophytic, feeding on decaying organic matter

ii. Parasitic, causing diseases in plants and animals

iii. Autotrophic, being able to produce food using energy from inorganic compounds -chemosynthesis.

Some bacteria are aerobic, some are anaerobic while some are facultative-can live in the absence or presence of oxygen.

Bacteria have the ability to reproduce rapidly by binary fission in which it copies the DNA it contains and then splits into two new cells.

FUNGI

Fungi are non green plants. They live as saprophytes, feeding on decaying organic matter or as parasites of plants and animals. They may be unicellular e.g yeast, or multicellular eg rhizopus,(bread mould), mushroom, penicillin which produces penicillin antibiotic

Structure of a fungus

The body of a multicellular fungus like bread mould consists of a mesh of finely branching threads known as Hyphae. Hyphae are not divided into cells. They are protected by cell wall composed of chitin, a complex carbohydrate. Each hypha has a cell membrane, cytoplasm with many nuclei and a large central vacuole. Fungi store carbohydrate as Glycogen.

Mode of life of Fungi

A unicellular fungus like yeast , may reproduce by budding. Fungi may reproduce by means of spores. The spores are minute and resistant to adverse environmental conditions eg drought. They are dispersed by wind and the settle on a suitable medium, they will germinate into new mycelia.

PROTOZOA

These microorganisms are microscopic, free living unicellular organisms. E.g Amoeba and paramecium. Some are parasites eg trypanosome and plasmodium.

ALGAE

They are microscopic green plants with majority found in aquatic environment. Examples are diatoms,Spirogyra, chlamydomonas, noctoc etc

Class Activity.

1. State two features of bacteria and fungi each
2. Name the type of reproduction carried out by bacteria
3. Are bacteria benefited or harmful to us?

TUESDAY, 07/07/2020

TOPIC: MICRO-ORGANISMS AROUND US.

Microorganisms are tiny/minute organisms which cannot being seen with the naked eyes except with the aid of microscopes. They are found everywhere-in the soil, in the water, on and inside our bodies like under the fingernails, mouth etc.

Groups of Microorganisms.

There are five groups or types of microorganisms:

1. Viruses
2. Bacteria
3. Protozoa
4. Fungi
5. Algae

VIRUSES

Viruses are the smallest microorganisms, they are too tiny that to be seen with ordinary microscope except with the use of electron microscopes.

Structure of a Virus.

Each cell of the virus consists of a strand of nuclear protein. It is made up of single strand of DNA or RNA. Some are enveloped or without envelop. Viruses do not have a cell structure. They may be rod-like or spherical in shape.

Mode of Life of Virus.

Viruses are boaderline between living and non-living things. They are only living while they are inside living cell and non-living while they are outside a living cell, this is because they lack cell structure. They can only reproduce inside a living cell, they form a crystal outside a living cell.

Examples are Adenovirus, Picornavirus, bacteriophage, coronavirus etc.

BACTERIA.

Bacteria are microorganisms that can be easily seen with light microscope. They occur in clusters or colonies.

Structure of a Bacterium.

A bacterium has a slimy capsule, cell wall, a cell membrane , dense cytoplasmic granules with no definite nucleus. It has nuclear material called DNA which spread through the cell.

CLASS ACTIVITY.

1. Study the mode of life of a bacterium and a virus, state two differences between them.
2. Mention five parts of a microscope

CORRECTION TO WEDNESDAY QUESTIONS

1. Tillage is the process of loosening the soil after the vegetation on a piece of land has been cleared. Tillage removes crop residue from the soil, leading to increased soil erosion. While pesticides are chemicals used in killing insects/ pests. Excess pesticides may be washed into the water bodies and accumulate in the bodies of aquatic organisms and their predators.
2. If the grasshopper is unable to excrete the pesticide/insecticide, the chemical will accumulate in its body. The snake feeds on many grasshoppers, and the insecticide will become more and more concentrated as it accumulates at the higher tropic levels in the food chain. The hawk will thus accumulate the highest concentration of pesticide.
3. Crop rotation.
4. Bush burning.

CORRECTION TO TUESDAY CLASS ACTIVITY

Differences between:

Thallophytes	Bryophytes
Absence of rhizoid	Presence of rhizoids ( root-like structures)
They are not diffirentiated into tissues	They are differentiated
They are found in the aquatic environment. Eg spirogyra	They are found in moist terrestrial environment. Eg moss and liverwort

Angiosperm	Gymnosperm
They are seed-bearing plants that produce flowers. They are flowering plants	They are seed-bearing plants that do not produce flowers.They are non-flowering plants
Seeds are enclosed in the fruits	Seeds are naked, borne a cone.
Examples are mango tree, water leaf, maize plant etc	Examples are pines,palm-like cycads, gingkos etc

WEDNESDAY, 01/07/2020.

Hello students, hope you are fine and active towards your class activities.

TODAY’S TOPIC: EFFECTS OF AGRICULTURAL ACTIVITIES ON ECOLOGICAL SYSTEM.

Some of the agricultural activities  carried out by  farmers  have some effects or consequences on the ecologic al system. Some of these agricultural practices are:

1. Bush burning
2. Overgrazing
3. Fertilizer application
4. Pesticide application
5. Tillage
6. Deforestation

Some of the farming activities  that have effects on the ecological system:

1. Monocroping
2. Continuous cropping
3. Shifting cultivation
4. Crop rotation
5. Mixed farming

NOTE: Study the effects of these agricultural or farming activities in your textbook.

CLASS ACTIVITY

1. Describe the effect of tillage and the usage of pesticides on the ecological system.
2. Green plants→Grashopper→Snake→Hawk.

From the example of food chain, explain how the practice of spraying pesticides can lead to birds of prey, like hawk, being harmed

3. The cultivation of different types of crops on a plot of land in a successive order is termed__________

4. Which of the agricultural practices contributes to the release of carbon dioxide?

30/06/2020 TUESDAY.

Hi students, hope you are preparing for ressumption. Its quite unfortunate that majority of you are not attempting these class activities. Well, its all for your success.

TOPIC; RELEVANCE OF BIOLOGY TO AGRICULTURE.

Biology and Agriculture are closely related subjects as both deal with plants and animals. Agriculture involves the cultivation of crops and rearing of animals for man’s use. While Biology involves the study of plants and animals. The knowledge from biology has being applied in the agricultural science, e.g in selective breeding of plants(ie cross-breeding of plants and animals with favourable characteritics that can produce offspring that are stronger and survive better) and animals, genetic engineering( ie the modification of certain genes of plants and animals to produce varieties of high quality , high yielding, longer shelf life and improved resistance to diseases).

Classification of Plants

Plants are generally classified based on three major criteria;

1. Based on Botanical/Scientific Clasification.
2. Based on Agricultural Classification
3. Based on Life Cycle

Based on Botanical Classifiction, we have;

a. Thallophyta e.g spirogyra

b. Bryophyta e.g Moss and Liverwort

c. Pteridophyta e.g Fern

d. Spermatophyta which involves Angiosperm e.g mango plant and Gymnosperm pine tree.

Based on Agricultural Classification or based on Uses, we have;

a. Cereal plants e.g rice, maize.

b. Pulses/ Legumes e.g beans, melon.

c. Root and Tuber crops e.g cocoyam, carrot.

d. Vegetable crops e.g spinach, okro.

e. Fruit crops e.g banana, mango.

f. Beverage crops e.g coffee, kola.

g. Spices e.g onion, ginger.

h. Oil crops e.g melon, coconut

i. Fibre crops e.g cotton, sisal.

j. Latex crops e.g rubber.

Based on Life Cycle.

a. Annuals: They are plants that grow, mature, produce fruits and die within one year. E.g maize, vegetable, groundnut, cowpea etc

b. Biennial: They plants that develop their vegetative parts during the first year and produce fruits and die in the second year. E.g carrot, onion, pepper etc.

c. Perennials: They are plants that grow , mature and produce fruits for more than two years. They can live for three to ten or over twenty years. E.g oil palm plant, mango plants, banana plant etc.

CLASS ACTIVITY

1. Write two differences between ; a. thallophyta and bryophyta and b. angiosperm and gymnosperm
2. Differentiate between cereals and pulses.

24/06/2020

CORRECTION TO WEDNESDAY QUESTION.

1. The answer to this lies in the second law of thermodynamic. It explains why the producers have the highest energy  and the amount of energy available to other consumers  decreases as  energy is lost as heat at each trophic level .
2. From plant.
3. Photosynthesis
4. The first law states that; energy cannot be created or destroyed but can be transformed from one form to another.

How  the first law affects energy flow in ecosystem;  Solar energy that enters an ecosystem is converted into chemical energy in the form of food  when plants carry out photosynthesis. T his energy is then transferred to  a herbivore when  it feeds on plants.When a carnivore feeds on the herbivore, the energy is transferred to the carnivore. Thus , energy is transferred from one organism to another along the food chain.

Wednesday, 24/06/2020.

Correction for tuesday’s questions.

1. The food chain above has five trophic levels.
2. The secondary consumer is the Lizard.
3. The organism with the highest energy is the Grass( the producer).
4. The organism with least energy is man.
5. The herbivore is the Grasshopper.
6. The organism that will form the base of the pyramid of energy is Grass.

WEDNESDAY, 24/ 06 /2020

LAWS OF THERMODYNAMICS AND ENERGY FLOW

The transfer of energy between organisms in an ecosystem is governed by two laws of thermodynamics which can be used to explain energy flow in the ecosystem.

The first law states that: energy can not be created nor destroyed but can be transferred from one form to another. E.g when firewood burns,the chemical energy in the firewood is converted into light and heat energy. The firewood has not been destroyed but transformed into another form.

The Second law state that every single transformation from one form to another is accompanied by a loss energy in the form of heat. This explains why producers have the highest amount of energy and the amount of energy available to other consumers decreases as energy is lost as heat at each trophic level.

Class Activity

1. If energy can not be destroyed, as stated by first law of thermodynamics ,why is it that the total amount of energy in the food chain becomes less at every trophic level?
2. State the source from which primary consumer obtains its energy.
3. Name the process by which energy enters the ecosystem
4. State first law of thermodynamics and explain how this law affects the flow of energy in an ecosystem.

TUESDAY. 24/06/2020

Hello students! Hope you are attempting your class activity.

CORRECTION FOR WEDNESDAY ACTIVITY

2 . The carnivores are lion and man

3. Cereal plant is called a producer because it contains chlorophyll and can manufacture its own organic food by photosynthesis

4. Through cellular respiration and excretion

TODAY’S TOPIC:ENERGY TRANSFORMATION IN NATURE.

As energy flows in ecosystems, it is transformed from one form into another. In the process of photosynthesis, the radiant energy of the sun is converted into chemical energy stored in the sugar molecule. From the sugar molecules, the plants make lipids, proteins and other body materials containing chemical energy. The plants need energy for the absorption mineral salts ,as well as for movement, synthesis, growth, reproduction, and other vital processes.

It obtains this energy through respiration, during which some molecules of carbohydrate, lipids or proteins are broken down and the chemical energy in them released. Part of this energy is used by the plants and part converted into chemical energy, which is lost to the environment. The chemical energy in the organic molecules of the producer is the energy for the primary consumer.

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ENERGY LOSS IN THE ECOSYSTEM.

Energy is lost at the earth’s surface in form of solar radiation, or from organisms during respiration and excretion. A large amount of energy is given out by the sun. About half of the radiant energy is absorbed by the cloud and ozone layer, small part is reflected, transmitted or radiated and much is converted into heat energy.

As much as 90%-99% of the radiation that reaches the plants is lost due to reflection, radiation or evaporation. Thus, only about 1% -10% of the radiation received by plants is available for use by the plants to be converted into chemical energy during photosynthesis.

Energy is lost to the environment as it is transferred from one trophic level to another. For example, when a herbivore feeds on a plants, not all of the energy is transferred to the animals. Some of the energy may be lost to the environment as heat ,egester, and excretory products

Therefore, energy is lost progressively at each trophic level along the food chain. The primary producer has the highest energy while the final consumer has the least energy.

Class Activity.

Grass- Grasshopper- Lizard-Hawk-Man.

Study the food chain above and answer the questions below,:

1. How many trophic levels does the food chain above contain?
2. Which of the trophic level is the secondary consumer?
3. Which of the organisms has the highest energy?
4. Name the organism with the least energy.
5. Which of the organism s is the herbivore?
6. Which of the organisms will form the base of the pyramid of energy?

WEDNESDAY 17/06/2020

Hi students, hope you are fine?

TODAY’S TOPIC: TROPIC LEVEL, PYRAMID NUMBER AND PYRAMID ENERGY.

Tropic Level is defined as the feeding level or each stage in a food chain or food web. It is the number of links by which food energy is transferred from producers to the final consumers. In the above constructed food chain, Grass is the first tropic level while snake is the fourth tropic level.

Pyramid of of Energy: This is defined as the amount of energy present in the living organisms at the different tropic level of the food chain. The energy decreases progressively from the first tropic level to the last tropic level, I.e the energy in the grass is much higher than the one in the snake. The energy loses along the food chain.

Pyramid of Number: This is the number of individual organisms at each trophic level which decreases progressively from the first tropic Lev to the last tropic level in the food chain.

Pyramid is a diagrammatic representation of food chain in which producers form the base and the carnivorous consumers form the apex.

Class Activity

Cereal-cattle- lion- man

Study the food chain above and answer the questions below:

1. Construct a pyramid of number on the food chain above
2. Which of the organisms is/are the carnivores?
3. why is the cereal called a producer?
4. State a process which is responsible for the loss of energy between one tropic level to another

16/06/2020. TUESDAY

Correction on last week questions:

1. Sandy soil has the least water retaining capacity because

a. The particles are large/ coarse this increases its porosity.

b. It lacks humus or organic matter that bind the soil together in order to retain water.

2. Porosity of soil is the ability of soil to allow liquid

or air to pass through it due to presence of tiny spaces between the soil particles.

Definitions of:

1. Turbidity: This is the cloudiness of water due to the presence of suspended particles. This prevents penetration of sunlight through the bottom of the water body
2. Salinity: This is the amount or concentration of salt solution in water body.
3. Hydrogen concentration (pH): This is the degree of acidity or alkalinity of water.
4. Factors that affect the relative humidity of an environment are:

a. The amount of moisture or water vapour in the atmosphere

b. The intensity of the sun.

CORRECTION FOR WEDNESDAY

2. Humus is a light ,damp and sticky solid mixture formed from decaying organic matter.

3. Humus is important for growing crops because it is rich in nitrate and is made up of colloids which absorb mineral salts essential for plant growth.

4. Air is important in the soil for roots respiration.

5. Sandy soil is unsuitable for plant growth because it is too porous and mineral salts are easily leached away.

TODAY’S TOPIC: FUNCTIONING ECOSYSTEM.

For any ecosystem to be functioning, the biotic components must interact with the abiotic components of the ecosystem.

AUTOTROPHS, HETEROTROPHS AND DECOMPOSERS.

Autotrophs: They are organisms that are able to produce complex organic food substances from raw materials such as water and carbon dioxide.

Types of autotrophs:

a. Photoaugotrophs: These are green plants that can convert light energy from sun into chemical energy and store it ad food molecules during Photosynthesis. They are also known as Primary Producers.

b. Chemoautotrophs: These are chemosynthetic bacteria that use chemical energy instead of light energy to manufacturetheir own food. They break down chemical compounds such as ammonia and hydrogen sulphide.

Heterotrophs: They are all animals, Carnivorous plants and most bacteria that can not produce their own food but depend on autotrophs. They are called Consumers

Decomposers: They are microorganisms (fungi and bacteria) that act on dead organisms. They breakdown dead organisms and cause decaying. They return nutrients back to the soil for plants .growth.

FOOD CHAIN AND FOOD WEB.

Food chain is defined as linear feeding relationship involving transfer of food energy from one organism to another. E.g

Grass-grasshopper-toad-snake

Food web is defined as a complex feeding relationship among organisms in the same habitat with two or more interrelated good chains. Food chains are linked together to form food web.

Challenge Activity.

1. Deduce the relationship between autotrophs, heterotrophs and decomposers.
2. Construct two food chains involving five organisms.

WEDNESDAY. 10/06/2020

Good day students, hope you are doing fine at home?

Topic: Simple Measurement of Ecological Factors.

Ecological factors that require measurement include:

Rainfall,temperature, wind,light,relative humidity, pH, turbidity, pressure, depth of water,slope etc.

These instruments include:

1. Rainguage:Used for measuring the amount of rainfall
2. Thermometer: Used to measure the temperature of the day
3. Anenometer: For measuring the speed of the wind.
4. Sacchi disc: Used for measuring the turbidity or transparency of the water.
5. Barometer: For measuring pressure .

Class Activity.

1. Mention other five ecological instruments and their uses.
2. What is Humus?
3. Why is humus important for growing crops?
4. What is the importance of air in the soil?
5. Explain why sandy soil is not suitable for plant growth.

TUESDAY 09/06/2020

Todayy topic: RELATIONSHIP BETWEEN SOIL TYPES AND WATER HOLDING EFFECTS OF THE SOIL ON VEGETATION

SOIL; It can be defined as the upper most part of the earth crust which provides support and nutrients for plant growth and habitat for some animals.

Types of Soil:

There are three major types:

Sandy soil,clayey soil and loamy soil.

Water Holding Capacity of Soil.

This is the ability of soil types like sandy soil, clay soil and loamy soil to retain water. Soil types have certain characteristics to retain water. For example clay soil had the highest ability to retain water due to its fine soil particles while sandy has to least retaining capacity due to its loose or large particles.

Factors Affecting Water Retaining Capacity.

1. Organic matter content
2. Soil texture
3. Clay content
4. Size of the soil particles
5. Mineral salts/ Soil pH.

Challenge Activity

1. Give two reasons why sandy soil has the least water retaining capacity among the soil types.
2. What do you understand by soil porosity.

Going through the last class activity, explain the following terms:

Turbidity, Salinity and hydrogen concentration (pH).

2. Mention two factors that can determine Relative humidity in the environment.

ECOLOGY

Sub-topic: ECOLOGICAL FACTORS COMMON TO ALL HABITATS

02/06/2020 TUESDAY

TOPIC: ECOLOGICAL FACTORS

Ecological Factors are those factors in the environment which can influence living organisms or cause changes in any habitat, be it aquatic or terrestrial habitat. For instance, coronavirus is an ecological factor( biotic factor) in the environment influencing human beings by causing them disease called covid-19. Any factor capable of causing changes in living organisms is an ecological factor. These factors are important to the populations of plants and animals living in a habitat.

Ecological factors are grouped into two:

1. Abiotic factors: They are non living factors affecting living organisms in the habitat. They influence the type of biotic community that is found in an area.They include:

i. Climatic factors; e.g temperature, wind, rainfall, sunlight, humidity,pressure etc.

ii. Chemical factors: e.g nutrients, water, oxygen, carbon dioxide etc.

iii. Edaphic factors:These consist of soil,soil water, its pH, its texture, its nutrient etc

iv.Topographic factors: These include the shape of surface of the earth e.g slopy, mountain, valley etc

2.Biotic Factors: These are the effects of other plants and animals on a given living organisms . Examples are:

i.Parasitism

ii. Predation

iii. Competition

iv. Patogen

v. Commensalism

vi.Disease

vii. Pest

viii .Food

ix.Mortality

x.Natality

CLASS ACTIVITY

1. Name six ecological factors which are biotic in an environment
2. List four major group of ecological factors which are abiotic in an environment and give two examples of each.

WEDNESDAY      03/06/2020

TOPIC: ECOLOGICAL FACTORS COMMON TO ALL HABITATS.

Ecological factors common to both aquatic and terrestrial habitats include;

1.Temperature

2. Rainfall

3.Light

4.Wind

5.Pressure

6. Hydrogen ion concentration

NB: Of these factors temperature and rainfall are the predominant factors that determine the major biomes of the world.

Ecological factors common to Aquatic  Habitat

They include:

1.Temperature

2.Rainfall

3. Wind

4.Light

5. Pressure

6. Density

7. Turbidity/transparency

8. Water current

9. Salinity

10.Dissolved gases     etc

Ecological Factors Common to Terrestrial Habitat.

They include;

1. Temperature
2. Rainfall
3. Wind
4. Light
5. Pressure
6. Hydrogen ion concentration
7. Relative humidty
8. Edaphic/ soil factors
9. Topographic factor/ land surface.

CLASS ACTIVITY

1. Explain the following;

Turbidity

Salinity

Hydrogen ion concentration

2.Mention two factors that can determine the relative humidty in the environment.

No Fields Found.

Correction to the class activity.

1a. Biosphere: is part of the earth occupied by living organisms(life). It can be found in the soil, water, land and air.

b. Hydrosphere:is part of the earth occupied by water. It comprises of all water bodies such as pond, lake, river etc.

c. Habitat:is a place whereorganisms(plants and animals) dwell or live which could be a pond, river, desert, savanna ora forest.

d. Population:It is a group of organisms or total number of organisms of same species living in a particular area.E.g population of Agama lizard in a given habitat.

e. Community: A community is a group of plants and animals that occupy a given area. It is made up of all populations of plants, animals and microorganisms living and interacting in a given habitat.

f. Ecological niche:It refers to the specific portion of habitat which is occupied by a particular organism and specific role/function it plays in the habitat.

2.Diffefences between tropcal rainforest and southern guinea savanna;

i.Tropical

Tropical Rainforest	SouthernGuinea S avanna
The vegetation has tall trees wiht evergreen leaves.	It has scattered tall decidious trees
It has high rainfall of over 200cm	It has moderate rainfall ofbetween 100 -150cm
It a forestland	It is a grassland
It has high temperature and high relative humidity	It has moderate temperature and moderate relative humidity

Mangrove swamp forest	Sahel savanna
It has the highest rainfall of over 250cm	It has low rainfall below 50cm
It has tall woody trees	It has short and tough shrubs/trees
Plant species found are red mangrove, white mangrove, coconut etc	Plant species are acacia, baobab, cactus etc
Possession of aerial roots for gaseous exchange	Absence of aerial roots

26/5/2020

BASIC ECOLOGICAL CONCEPTS

L.earning objectives: By the end of the lesson, you should be able to:

1. Define ecology and ecosystem.
2. Name the components of ecosystem.
3. Mention major local biotic communities in Nigeria.

Definition of ecology

Ecology is the study of plants and animals in relation to their environment. It is the study of interactions among organisms and between organisms and the physical and chemical factors making up their external environment.

Definition of ecosystem

An ecosystem is defined as community of plant and animals functioning together with their non-living environment. It is the combination of a community and the physical and chemical factors making up its non living environment. In order words, ecosystem consists of the living factors(plants and animals) interacting with the non-living factors in an environment.

Components of ecosystem

An ecosystem is made up of two main components. These are:

1. Abiotic components: The abiotic components of an ecosystem are the non- living things which include:

a. Climatic factors.e.g temperature, wind, sunlight, humidity, rainfall. etc.

b. Inorganic factors. e.g. nutrients, that is, carbon4oxide, oxygen, nitrogen, phosphorus and water.

c. Edaphic factors. e.g. soil, soil pH, soil water. etc.

d. Topographic factors. These refer to the shape of the land. i.e, sloppy, undulating, valleys, mountains,etc.

2. Biotic components: The biotic components of an ecosystem include the living things(plants and animals) which can be grouped into

a. The producers: producers are autotrophs or the green plants and some microorganisms that can manufacture their own food from simple inorganic materials during the process of photosynthesis and chemosynthesis.

b. The consumers: These are heterotrophs (animals and some plants) which cannot produce their food but depends directly or indirectly on plants for their food.

c. The decomposers: These are bacteria and some fungi which break down dead plants and animals in order to feed on them and in the process, nutrients are released to the soil for use by the producers.

Local biotic communities or biomes in Nigeria

A biome is a large region on the earth where vegetation grows. It is characterised by distinct climate, soil as well as the type of plants and animals found in it. A biome may consist of thousands of ecosystem.

The local biotic communities in Nigeria can be grouped into six:

1. Mangrove swamp forest
2. Tropical rain forest
3. Southern guinea
4. Nothern guinea savanna
5. Sudan savanna
6. Sahel savanna

Class activity:

1. Find out the meaning of the following ecological terms:

a. Biosphere

b. Hydrosphere

c. Habitat

d. Population

e. Community

d. Ecological niche

2. Write four differences between:

a. Tropical rainforest and southern guinea savanna.

b. Southern guinea savanna and northern guinea savanna.

c. Mangrove swamp forest and sahel savanna.

3. Name the ecological factor that the following instruments measure:

a. Wind vane

b. Secchi disc.

c. Barometer

d. Anemometer

e. Hygrometer

f. Thermometer

g. Photometer

No Fields Found.

Hello my students, hope you are staying safe?

Topic; Supporting Tissues in Plants.

Plants generally have structures that enable them to stand erect, give shape, strength, rigidity, flexibility and withstand external forces such wind and water.

Types of supporting Tissues in Plants.

The major ones are;

1.Parenchyma Tissue

2. Collenchyma Tissue

3.Sclerenchyma Tissue (Fibre)

4.Xylem(wood)

5.Phloem

For better understanding of these tissues, the following heads are employed;

-Location

-Structures

-Functions

PARENCHYMA TISSUE;

Location; It is found in the cortex of stem,phloem, root, leaf,mesophyll and xylem.

Structure; parenchyma cells are living plant cells with cellulose cell walls and many air spaces within them.They have large vacuoles filled with cell sap.

Functions;

1. When parenchyma cells (vacuoles) are filled with water/sap , it becomes tugid. This provides support and maintains the shape, firmness and turgidity of the stem of herbaceous plants .

2. They play important role in photosynthesis

3. They can also store starch and water.

COLLENCHYMA TISSUES

Location; They are found in cortex of stem, root, and hypodermis just below the epidermis.

Structure; They are also living cells. The cells are flexible and thus allow bending and twisting strains to which the stems, roots and leaves of plants are often subjected.

Functions;

1. They provide strength and supports in young growing plant parts such as stem, petioles, and leaf blades.

2. they gives flexibility and resilence to plants, i.e able to bend without breaking.

SCLERENCHYMA TISSUES

Location; These cells are mainly found in the pericycle in the vascular tissues and cortices of the roots and stems.

Structure; Sclerenchyma tissues are mainly made up of dead cells with cell walls that are filled with cellulose and lignin (there are two types; fibres and sclereids).

Functions:

1.They give flexibility to plants and prevent them from breaking up easily.

2. They provide strength, rigidity, hardness and support to plants.

XYLEM TISSUES

Location:They are found in the vascular tissues of stems, roots and leaves.

Structure: Xylem tissue is made up of many cells. They are;Tracheids, Vessels, Fibres and Xylem parenchyma.

Functions:

1.Xylem tissue conducts water and dissolved mineral salts from the roots to the stems, and leaves, and thereby providing mechanicl support within the plants.

2.It also gives strength and shape to plants

PHLOEM TISSUES

Location:They are also found in the vascular tissues of roots, stems and leaves plants.

Structure: T hey are made up of four cells-Sieve tubes, Phloem parenchyma, Phloem fibres and Companion cells.

Functions:

1.They conduct manufactured food of photosynthesis from their area of synthesis(leaves) to areas where they are needed.

2.They also give support to plants.

ASSIGNMENT (NB. Make sure you indicate the subject in the box provided for the answer)

1. Mention one function each of fibre and sclereid.
2. What is translocation?
3. Deduce two differences between collerenchyma and sclerenchyma tissues.
4. Mention two functions of supporting tissues in plants and five functions of supporting tissues in animals.

No Fields Found.

GROWTH 12/05/2020

Hello my dear students, how has been your holiday? Its a great moment with you and you will enjoy it. I will like to revise a topic; Growth.

Growth is one of the characteristics of living organisms. For growth to occur the rate of anabolic must exceed the rate of catabolic reaction ie rate of building up must exceed the rate catabbolic processes.

Can you still recall examples of catabolism and anabolism?

Growth is defined as the increase in size or complexity of an organism due to the addition of new protoplasm.

Basis of Growth.

They are ;Cell Division, Cell Enlargement and Cell Differentiation.

Cell division ;it is the division of a single cell into two identical daughter cells. it results in an increase in cell number.

Types of Cell division;

Mitosis and Meoisis.

Mitosis ;is a cell division which involves duplication of chromosome whereby each daughter cell has exactly the same chromosome content as the parent. For multicellular organisms to grow , new cells must be synthesized by mitosis. For example ,skin cells must divide regularly to replace dead cells that have been shed from the surface of the skin. Dead cells are constantly being replaced by the process of mitosis. Mitosis results into two daughter cells.

No Fields Found.