INSTRUCTIONS
- All Questions are Compulsory
- Write your Answers in the Spaces Provided
- Wrong Spelling of Technical Terms shall be Penalized
Max Score |
Student’s Score |
80 |
QUESTIONS
- The diagram shown below represents a nuscleus
- State the role of the organelle labelled Q (1mk
- Name a Kingdom whose members lack structure labelled P (1mk
- Which is the general term given to organisms whose cells have structure P? (1mk
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- Name the TWO components of a lipid molecule (1mk
- State TWO disadvantages of using fats as respiratory substrates (2mks
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- Name the pigment that protects humans from the negative effect of Ultraviolet lights (1mk
- Explain how sunlight contributes to stronger bones and teeth in human beings (2mks
- Name the main target organ of the following hormones: (2mks
- Aldosterone
- Insulin
-
- What is asexual reproduction? (1mk
- Give TWO disadvantages of sexual reproduction (2mks
- The diagram shown below represents a seeding Use it to answer questions that follow
- Give a reason why the plant above is a member of Class Dicotyledonae (1mk
- Explain why the biomass of part labelled A will be lower compared to the one found in the seed stage of the same plant (2mks
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- State TWO ways in which blood clotting is important to a human being (2mks
- What are the roles of thrombokinase enzyme during blood clotting? (2mks
- The diagram shown below represents a flower
- Name the agent of pollination for the flower shown above (1mk
- Give TWO reasons for your answer in a) above (2mks
- State the differences between cones and rods in terms of the following (2mks
Feature
Cone
Rod
Visual acuity
Photochemical
- Use the diagram of a nerve cell shown below to answer questions that follow
- With a reason, give the identity of the nerve cell (2mks
Identity
Reason - Explain the significance of absence of part labelled H in nerve cells found in the brain (2mks
- With a reason, give the identity of the nerve cell (2mks
- Give THREE features that make modern man to be more adaptable to the environment (3mks
- The diagram below represents a living organism
- State TWO economic importance of the above organism in the food industry (2mks
- Why does the rate of respiration reduce under the following conditions? (2mks
- Low temperature
- Metabolic poison
- State TWO reasons why Biotechnology is important in modern science (2mks
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- Fill in the table shown below to give differences between continuous and discontinuous variation (2mks
Continuous Variation
Discontinuous Variation
- Explain how variation is important in the process of evolution? (3mks
- Fill in the table shown below to give differences between continuous and discontinuous variation (2mks
-
- Define the term species (1mk
- State TWO contributions of Carolus Linnaeus (1708 – 1778) to taxonomy (2mks
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- In an experiment, Peter counted 9 cells along the diameter of field of view of a light microscope measuring 30mm Determine the diameter of one cell in micrometers (3mks
- Why is electron microscope safer to the eye than light microscope during use? (1mk
- The following diagram represents results of an experiment carried out on two sets of germinating seeds
- Account for the result shown in test tube X (2mks
- What is the importance of dipping the boiled seeds in a disinfectant in test tube Y? (1mk
- The diagram shown below represents a section of the vertebral column
- Name the part labelled S (1mk
- State TWO ways in which part T is important to movement in human beings (2mks
- Describe how the following cells adapt the structures where they are found to their functions
- Companion cell (2mks
- Schwann cell (2mks
- A mother had a still birth and the expelled foetus showed clear signs of anaemia and jaundice
- Give the name of this disorder (1mk
- Describe how the disorder arose (3mks
- The following equation represents a section of the Nitrogen Cycle
- Name:
- Bacterium labelled Y (1mk
- Compound X (1mk
- Explain how Process Z affect plant growth in an area? (2mks
- Name:
- Samson had a road accident resulting in serious head injuries that left him with the following conditions: Loss of balance, low body temperature; poor speech, unregulated breathing and memory loss Name the part of the brain affected that led to the following:
- Low body temperature ,,(1mk
- Memory loss (1mk
- Unregulated breathing (1mk
- The graph shown below represents effect of substrate concentration on rate of enzymatic reaction
- Account for the rate of enzymatic reaction when the substrate concentration was between 03 to 05% (2mks
- Name the substrates for the following enzymes
- Carbonic anhydrase (1mk
- Thrombin (1mk
- A tilapia fish has a full length of 300mm but measures 200mm from the mouth tip to its anus Determine the tail power of the fish (2mks
MARKING SCHEME
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- Manufacture of ribosomes;
- Monera;
- Eukaryotes;
-
- Glycerol; Fatty acids;
- Requires a lot/more Oxygen to oxidise; Insoluble in water thus not easy to transport to respiratory site;
-
- Melanin;
- Influences formation of Vitamin D (in the body); Which is required for absorption of phosphates and calcium ions; important in bone and teeth formation.
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- Kidney;
- Liver;
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- Process where new off-springs arise without fertilization;
- Slower/takes longer time to obtain off-springs; Rely on unpredictable pollination/fertilization that are easily affected by weather changes; variation may lead to disadvantageous traits; Relies on the presence of both parents that may be possible in some cases e.g when one dies;
-
- Has a taproot;
- Stored nutrients are hydrolysed/converted to simpler forms; that are used in cell division/growth (of the seedling);
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- Prevent excessive loss of blood/anaemia; Prevent entry of pathogens into the body; Initiate healing of wound;
- Convert prothrombin to thrombin; Neutralises anti-clotting factor/Heparin;
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- Wind; Reject Wind-pollinated
- Has feather-like stigma; Long filament/Androecium hangs outside; Reduced petals/bracts to expose the gynoecium/androecium to wind;
-
Feature
Cone
Rod
Visual acuity
High
Low;
Photochemical
Iodopsin
Rhodopsin;
-
- Identity: Sensory; Reject Unipolar
Reason : Unipolar; Cell body off the axon; - Slow down movement of impulse; to give adequate time for interpretation of the impulse (by brain/CNS);
- Identity: Sensory; Reject Unipolar
- High level of intelligence/Reasoning/Brain capacity; Well-developed speech/effective communication abilities; Upright gait to see far/danger easily; Bipedal locomotion frees hands for other uses; pre-hensile hands for handling various tools; non-opposable toe for stability; 1st 3
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- Baking/Manufacture of bread; Brewing Alcoholic beverages; Manufacture of high nutritional value proteins/Single Cell Protein; Manufacture of biofuel/gasohol; Food flavouring; Food conditioning/Preservation; Making vitamin supplements; Ripening of cheese; Food spoilage; Mark 1st2
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- Respiratory enzymes are inactivated;
- Bind to the enzymes permanently or temporarily thus inhibit enzyme action on substrates;
- Development of new tools/techniques/procedures for biological research; Development of materials for medicine/agriculture/health/industries
Accept specific examples e.g Drugs/Medicine/Hormones/Vaccine/Cultivars -
-
Continuous Variation
Discontinuous Variation
Determined by interaction of many genes
Determined by one or two genes;
Determined by interaction between genes and the environment
Determined by the genes alone;
Has intermediate traits between two extremes
Lack intermediates/Has distinct groups;
- Organisms with disadvantageous variations are eliminated; those with advantageous variations adapt, survive (and reproduce); accumulation of such variations over time may lead to speciation/emergence of a new species;
-
-
- A group of organisms that are structurally similar and freely interbreed to give rise to a fertile/viable offspring;
- Came up with binomial nomenclature; Pioneered Modern/Natural classification/taxonomy;
-
- d
9cells measure 3.0mm
Therefore 1cell will measure: (1cell x 3.0mm)/9cells = 0.333mm;
1mm = 1000micrometers
Thus 0.333mm = (0.333mm x 1000micrometers)/1mm;
Diameter of a cell = 333micrometers; - Viewing of images is indirect/on screen;
- d
-
- Germinating seeds utilized Oxygen in respiration; the released Carbon (IV) oxide was absorbed by Potassium hydroxide solution; (Thus reduces volume of air in the tube and level of coloured liquid rises)
- To preserve/Prevent decomposition/Anaerobic respiration;
-
- Neural spine; Reject Spine alone
- Create vertebral column flexibility; Absorb shock; Reduce friction/rubbing together of the adjacent vertebrae; Mark 1st 2
-
- Has numerous mitochondria to generate a lot of energy; for translocation of substances in the phloem;
Large cytoplasm to store a lot of nutrients; used in respiration to supply energy for translocation; - Release myelin sheath; which insulates the axon;
- Has numerous mitochondria to generate a lot of energy; for translocation of substances in the phloem;
-
- Erythroblastosis foetalis/Haemolytic disease of the newborn;
- Arises when a Rhesus negative mother carries a subsequent Rhesus positive foetus’ pregnancy; particles of foetal erythrocytes pass to the mothers blood leading to formation and accumulation of anti-Rhesus antibodies; which pass to the foetus via placenta causing antibody-antigen reaction that destroy the foetal erythrocytes;
-
-
- Nitrobacter sp; Nitrococcus sp
- Nitrates;
- Low growth; due to loss of soil fertility/Nitrates important in protein synthesis;
-
-
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- Hypothalamus;
- Cerebrum;
- Medulla oblongata;
-
-
- No further increase in rate of reaction/Constant; Since other factors were limiting;
-
- Carbon (IV) Oxide;
- Fibrinogen;
- Tail power = {(300mm - 200mm)/300mm} x 100;
= 33.3%;
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