INSTRUCTIONS TO CANDIDATES
- Answer all the questions in this paper in the spaces provided.
Questions
ATTEMPT ALL THE QUESTIONS
- Some form one students wanted to collect the following animals for study in the laboratory. State the suitable apparatus they should use.
- Housefly (1 mk)
- Scorpion (1 mk)
- Ants (1 mk)
- State two reasons why a snake is classified as a reptile. (2 mks)
-
- Explain the role of oxygen in Active transport (1mk)
- Name two processes that depend on Active transport in animals (2mks)
- Explain how sunken stomata lower the rate of transpiration (2mks)
- State how xylem vessel is adapted to its function (3mks)
-
- Define the term immunity. (1mk)
- Distinguish between natural immunity and acquired immunity. (1mk)
- Identify one immunizable disease in Kenya. (1mk)
-
- State two adaptations of the alveolus to its functions. (2mks)
- Suggest a reason for asthmatic patient producing a wheezing sound during breathing? (1mk)
- What is the significance of the cartilage found in the human trachea being incomplete (c- shaped rings) (1mk)
- Define the following terms;
- Inter specific competition. (1mk)
- Carrying capacity (1mk)
- Suggest two methods that can be used to determine the type of food eaten by animals. (2mks)
-
- State one significance of genetics counseling (1mk)
- Part of a strand of DNA molecules was found to have the following sequence A-T-C-G-G-G-A-T-C-T. What is the sequence?
- Of the complementary strand? (1mk)
- On a m- RNA strand copied (1mk)
- The paddles of whales and the fins of fish adapt these organisms to aquatic habitats.
- Name the evolutionary process that may have given rise to these structures. (1mk)
- What is the name given to such structures? (1mk)
- Give two examples of vestigial organs in man. (2mks)
- Name the organelles that carry out the following functions (4mks)
- Destroy old and worn-out organelles
- Formation of spindle fibres
- Osmoregulation
- Selective passage of substances into the cell
-
- Why would you give an athlete glucose and not sucrose after a race? (1mk)
- What happens to lactic acid after oxygen debt recovery? (2mks)
- State the difference between glycolysis and kreb”s cycle based on the following.
- where they occur . ( 1 mk)
- Amount of energy produced. ( 1 mk)
- End product(s) (1 mk )
-
- Under which of the following magnifications would one see a larger part of the specimen X40 0r X500? Give a reason. (2 mks)
- State how magnification is worked out in a light microscope. (1 mk)
- The illustration below shows a transverse section through a mammalian kidney.
- Name the structures labelled X and Y. ( 2mks)
- State the process in Q that leads to the formation of glomerular filtrate. (1mk)
- State one function of sebum (1 mk)
- Name the structures labelled X and Y. ( 2mks)
- State three differences in composition between umbilical artery and umbilical vein. (3 marks)
Umbilical vein Umbilical Artery -
- What is meant by the term taxonomy? (1mk)
- When are two organisms considered to belong to the same species. (2mks)
- The diagram below shows part of alimentary canal of a mammal
- Name the parts labeled A and C (2mks)
- State the function of the part labeled B. (1mk)
- The graph below shows the relationship between body temperatures and external temperatures in a human being and a snake. Study it and answer questions that follow.
- What happens to the temperature of each organism as the external temperature increases. (2 mks)
Human –
Snake – - Humans are described as homoithermic. State the advantage of this condition. (2mks)
- What happens to the temperature of each organism as the external temperature increases. (2 mks)
-
- State three differences between light stage and dark stage of photosynthesis. (3 mks)
Light stage Dark stage
- State three differences between light stage and dark stage of photosynthesis. (3 mks)
- Define;
- Pulmonary circulation (1mk)
- Systemic circulation (1mk)
- The diagram below represents a plant cell that was subjected to a certain treatment.
- Account for the shape of the cell at the end of the experiment. (2 mks)
- Draw a diagram to illustrate how an animal cell would appear if subjected to the same treatment. (1mk)
-
- Give a reason why each of the following steps are followed when preparing cross sections of a leaf for examination under a microscope.
- Cutting thin sections. (2 mk)
- Placing the sections in water. (1 mk)
- Give a reason why each of the following steps are followed when preparing cross sections of a leaf for examination under a microscope.
- Explain why the population of people with sickle cell anaemia is higher in malaria prone areas. (3mks)
- The diagram below is of a stage in cell division
With a reason identify the stage.
Stage (1 mk)
Reason (1 mk) - The graph below represents growth pattern in a group organism
- Name the type of growth curve (1 mk)
- Name the phylum that shows this type of pattern (1 mk)
- State one disadvantage of this type of pattern (1 mk)
Marking Scheme
- Some form one students wanted to collect the following animals for study in the laboratory. State the suitable apparatus they should use.
- Housefly (1 mk)
- Sweep net;
- Scorpion (1 mk)
- pair of forceps;
- Ants (1 mk)
- pooter
- Housefly (1 mk)
- State two reasons why a snake is classified as a reptile. (2 mks)
- skin is dry and covered by a horny/leathery scales
- fertilisation is internal
- are ectothermic/poikilothermic
- use lungs for gaseous exchange
-
- Explain the role of oxygen in Active transport (1mk)
- Oxidize food to produce energy required in active transport rej to produce energy
- Name two processes that depend on Active transport in animals (2mks)
- Reabsorption of sugar and some salts by kidney;
- Absorption of digested food from alimentary canal;
- Excretion of waste products from body cell;
- Transmission of nerve impulse.
- Explain the role of oxygen in Active transport (1mk)
- Explain how sunken stomata lower the rate of transpiration (2mks)
- Form pits that accumulate moisture; lowering saturation deficit between the atmosphere and sub stomatal airspaces; reducing transpiration.
- State how xylem vessel is adapted to its function (3mks)
- Lignified walls to prevent them from collapsing /offer support
- Hollow and tubular for continuous flow of water;
- Narrow to enhance capillarity;
- Made of dead cells; /to reduce water demand
-
- Define the term immunity. (1mk)
- Ability of the body to identify/ recognize foreign antigens and develop mechanisms of destroying them. / ability to resist infection;
- Distinguish between natural immunity and acquired immunity. (1mk)
- Natural immunity is inborn /inherited /passed from parents to offspring while acquired immunity is obtained in life;
- Identify one immunizable disease in Kenya. (1mk)
- Tuberculosis;
- poliomyelitis;
- diphtheria;
- whooping cough;
- measles;
- hepatitis
- Covid -19
- Define the term immunity. (1mk)
-
- State two adaptations of the alveolus to its functions. (2mks)
- Thin epithelium for reduction of diffusion distance of respiratory gases;
- Highly vascularized to transport gases/maintain a steep concentration gradient;
- Moist surface to dissolve respiratory gases so that they diffuse in solution form;
- Suggest a reason for asthmatic patient producing a wheezing sound during breathing? (1mk)
- This is because muscles around the bronchioles contracts and so reduce their diameter.
- What is the significance of the cartilage found in the human trachea being incomplete (c- shaped rings) (1mk)
- To permit swallowing in the oesophagus ;
- State two adaptations of the alveolus to its functions. (2mks)
- Define the following terms;
- Inter specific competition. (1mk)
- Competition between individuals of different species (inhabiting the same ecological area)
- Carrying capacity (1mk)
- Maximum number of organisms an area can comfortably support with depletion of available resources
- Inter specific competition. (1mk)
- Suggest two methods that can be used to determine the type of food eaten by animals. (2mks)
- Analyzing animal droppings
- Direct observation of the animal while feeding
- Dissection and analysis of the gut content
- Dentition
-
- State one significance of genetics counseling (1mk)
- Provides information and advice to enable the victim to arrive at an informed decision on their genetic make up./disoders.
- Part of a strand of DNA molecules was found to have the following sequence A-T-C-G-G-G-A-T-C-T. What is the sequence?
- Of the complementary strand? (1mk)
- T-A-G-C-C-C-T-A-G-A
- On a m- RNA strand copied (1mk) U-A-G-C-C-C-U-G-U
- Of the complementary strand? (1mk)
- State one significance of genetics counseling (1mk)
- The paddles of whales and the fins of fish adapt these organisms to aquatic habitats.
- Name the evolutionary process that may have given rise to these structures. (1mk)
- Convergent evolution;
- What is the name given to such structures? (1mk)
- Analogous structures;
- Give two examples of vestigial organs in man. (2mks)
- Coccyx; appendix; reduced ear muscles/nictating membrane/reduced body hair;
- Name the evolutionary process that may have given rise to these structures. (1mk)
-
- lysosomes
- Centrioles
- Contractile vacuoles
- Cell membrane
-
-
- Glucose is highly soluble in water/ (blood) hence is faster and easily transported to the respiratory sites;
- Glucose is very simple in structure than sucrose hence easy to oxidize to yield energy to the body cells;
- it is oxidized to release energy;
-
- State the difference between glycolysis and kreb”s cycle based on the following.
- where they occur . ( 1 mk)
- Krebs cycle occur in the matrix of the mitochondrion while glycolysis occurs in the cell cytoplasm
- Amount of energy produced. ( 1 mk)
- Glycolysis- less energy/2ATP molecules/210kJ Produced;
- Kreb’s cycle- more energy produced/ 38 ATP molecules/2880kJ
- End product(s) (1 mk )
- Glycolysis- pyruvate/pyruvic acid
- Kreb’s cycle- energy, water and carbon (IV) oxide (all as one correct)
- where they occur . ( 1 mk)
-
- X40
- Has a lower magnification giving a wider field of view
- Total magnification= Eye piece lens magnification X Objective Lens Magnification
- X40
- The illustration below shows a transverse section through a mammalian kidney.
- Name the structures labelled X and Y.
- X - Cortex
- Y - Medulla
- State the process in Q that leads to the formation of glomerular filtrate. (1mk)
- Ultrafiltration ;
-
- Moisten the skin/makes the skin supple;
- Antiseptic/kills pathogens/bacteria
- Name the structures labelled X and Y.
- State three differences in composition between umbilical artery and umbilical vein. (3 marks)
-
- What is meant by the term taxonomy? (1mk)
- It is the science/study of classification/grouping of organisms (into respective ranks/units using their characteristics)
- When are two organisms considered to belong to the same species. (2mks)
- When they can freely/naturally interbreed; to give rise to viable/fertile offspring;
- What is meant by the term taxonomy? (1mk)
- The diagram below shows part of alimentary canal of a mammal
- Name the parts labeled A and C (2mks)
- A - Duodenum
- C - Oesophagus /gullet (reject food pipe)
- State the function of the part labeled B. (1mk)
- Temporally storage of feaces / undigested /indigestible materials/Absorption of water;
- Name the parts labeled A and C (2mks)
- The graph below shows the relationship between body temperatures and external temperatures in a human being and a snake. Study it and answer questions that follow.
- What happens to the temperature of each organism as the external temperature increases. (2 mks)
- Human – remains constant;
- Snake – increases;
- Humans are described as homoithermic. State the advantage of this condition. (2mks)
- enables them to be active throughout;
- enables them exploit different habitats;
(any one 1mk)
- What happens to the temperature of each organism as the external temperature increases. (2 mks)
- State three differences between light stage and dark stage of photosynthesis. (3 mks)
light stage Dark stage -Occur in presence of light
-Occur in grana
-produce hydrogen atoms and oxygen gas-Occur any time
-Occur in stroma
-Produce glucose - The diagram below represents a plant cell that was subjected to a certain treatment.
- Account for the shape of the cell at the end of the experiment. (2 mks)
- Plant cell was placed in hypertonic solution to its cell sap, it lost water by osmosis: it became plasmolysed
- Draw a diagram to illustrate how an animal cell would appear if subjected to the same treatment. (1 mk)
- Account for the shape of the cell at the end of the experiment. (2 mks)
-
- Give a reason why each of the following steps are followed when preparing cross sections of a leaf for examination under a microscope.
- Cutting thin sections. (1 mk)
- To reduce the layers of cells/sections preventing overlapping hence better penetration of light ( for illumination)
- Placing the sections in water. (1 mk)
- To avoid drying up which may distort the cells;
- To maintain turgidity of the cells
- Explain why the population of people with sickle cell anaemia is higher in malaria prone areas. ( 3 mks)
- Their red blood cells carry defective haemoglobin (type S) which carries little or no oxygen;
- Plasmodium do not survive in their red blood cells hence survive malaria attack; they reproduce successfully giving rise to more population;
- Cutting thin sections. (1 mk)
- Give a reason why each of the following steps are followed when preparing cross sections of a leaf for examination under a microscope.
- The diagram below is of a stage in cell division
With a reason identify the stage.- Stage (1 mk)
- Prophase I
- Reason (1 mk)
- Chromatids cross over each other at chiasmata
- Formation of a bivalent
- Stage (1 mk)
- The graph below represents growth pattern in a group organism
- Name the type of growth curve (1 mk)
- Intermittent
- Name the phylum that shows this type of pattern (1 mk)
- Arthropoda
- State one disadvantages of this type of pattern (1 mk)
- Hardened exoskeleton limits the growth/size of the organism
- Name the type of growth curve (1 mk)
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