Biology Paper 1 Questions and Answers - Form 4 Opener Term 1 Exams 2022

BIOLOGY
PAPER 1

Instructions.

• Answer all the questions in the spaces provided.

Questions

1. Name the element obtained from insects by insectivorous plant. (1mk)
2. State two function of centrioles in a cell. (2mks)
3. Study the diagram below and answer the questions that follow.
   
   
   1. Identify the structure. (1mk)
   2. Name the part labeled A and B. (2mks)
4. State the function of each of the following part of the light microscope. (2mks)
   Mirror
   Fine adjustment knob
5. Water logging can cause the death of some plants. Explain. (2mks)
6. The diagram below shows a process that takes place in the gullet swallowing of food.
   
   
   1. Name the process. (1mk)
   2. Name : (2mks)
      1. The muscle labeled X
      2. The part labeled Y
7. The equation below shows a process that takes place in mammals.
   Amino acids Organic compound + urea
   1. Identify the process. (1mk)
   2. State the significance of this process to a mammal. (1mk)
8. State the function of co-factors in cell metabolism. (1mk)
9. Name two gaseous exchange structures in higher plants. (2mks)
10.          
    1. Give three structural differences between wind and insect pollinated flowers. (3mks)
    2. State the significance of cross pollination. (1mk)
11. Explain how much of the following factors would lead to population increase of species in an ecosystem. (3mks)
    1. Competition
    2. Predation
    3. Parasitism
12. Name three support tissues in higher plants. (3mks)
13.          
    1. Why are plants said to be primary producers in a natural habitat. (1mk)
    2. Where does the digestion of fats in a mammal start. (1mk)
14.        
    1. Name two structures in a flower that wither off after fertilization. (2mks)
    2. Apart from withering, name two other changes that occur in flowers after fertilization. (2mks)
15. The equation below shows a chemical reaction that takes place in plants.
    Carbon (IV) Oxide + water Glucose + A
    1. Identify A
    2. Other than reactants, state two conditions necessary for this reaction. (2mks)
    3. Name the process represented by the equation. (1mk)
16. The diagram below show the growth pattern in a grasshopper.
    
    
    1. Briefly explain the type of the shape of the graph. (2mks)
    2. Name the regions labeled M and N. (1mk)
17. Define eutrophication. (3mks)
18. Define counter current flow system as used in gaseous exchange in a fish. (2mks)
19. The diagram below shows a phenomenon which occurs during cell division.
    
    
    1. Name the parts labeled A and B. (2mks)
    2. State the biological importance of the part labeled B. (1mk)
    3. Identify the type of all division in which this phenomenon occurs. (1mk)
    4. Name the organs in human being in which the phenomenon occurs. (1mk)
20. Name metabolic wastes of birds. (2mks)
21. Name the organism that causes malaria in human beings. (1mk)
22. Giving examples distinguish between continuous and discontinuous variation. (4mks)
23. State three differences between deoxyribonucleia acid (DNA) and Ribonucleic acid (RNA) (3mks)
24. Identify two causes of variation. (2mks)
25. State three causes of variation. (2mks)
26. What is parthenocarpy? (1mk)
27. Explain four roles of auxin hormone in growth and development of plants. (2mks)
28. State three differences between diffusion and active transport. (3mks)
29. State three structural modifications of nephrones in dessert mammals. (3mks)
30. State two adaptation of leaves in arid and semi-arid areas. (2mks)

Marking Scheme

1. Nitrogen
   
   
2.         
   • They are involved in cell division
   • They are involved in the fromation of villa and flagella
     
     
3.              
   1.         
      • Cell membrane
      • A- protein layer
        B- lipid layer
        
        
4. Mirror - reflects light rays through the hole on the stage onto the specimen
   Fine adjustment knob - raises/ lowers the body tube to  bring the image into sharp focus
   
   
5. Water logging reduces the O2 concentration in the soil hence plants die due to lack of O2 for respiration.
   
   
6.           
   1. Peristalsis
      
      
   2.        
      1. Gut muscles (circular and longitudinal muscles)
      2. Food bolus
7.           
   1. Deamination
   2. Controls/ regulates excess amino acids in the body
      
      
8. They activate the enzyme
   
   
9. Stomata
   Lenticell
   
   
10.              
    1.   
       

       Insect	Wind
       They have large, heavy, sticky pollen grains large and conspicuously coloured petals	Small, smooth , light pollen grains, Small inconspicuous petal
       Usuallly have nectar	Lack nectar
       Anthers are small and timely attached	Large anthers and loosely attached
       Samll Sticky stigmas	Long feathery stigma

    2. Leads to variations thus increase in arrival of the spp
       
       
11.                  
    1. Less competition for resources like water and food result to increase in population
    2. Decrease of predators increase the number of a prey
    3. Presence of fewer parasites lead to an increase host population
       
       
12.                  
    • Xylem vessels, xylem tracheids
    • Parenchyma
    • Scelerenchyma
    • Collenchyma
      
      
13.            
    1. They manufacture organic compounds from simple inorganic substances
    2. Duodenum
       
       
14.          
    1.           
       • Stigma
       • Style
       • Stamen
       • Petals
         
         
    2.              
       • The zygote becomes the embryo
       • The ovule becomes the seed
       • Ovule integuments becomes the seed coat
       • The ovary becomes the fruit
       • The primary endosperm becomes the seed
15.                    
    1. Oxygen
       
       
    2.          
       • Sunlight
       • Energy
       • Chlorophyll
       • Optimum temperature
         
         
    3. Photosynthesis
       
       
16.            
    1. Intermittent growth curve, grasshopper has exoskeleton which hinders expansion once its shade it allows growth
       
       
    2. M- Moulting phase
       N - growth phase
17.   Increase in plant growth in water bodies due to increase in nutrients/ resources that promote plant/ algal growth.           
18.   Counter current exchange is the mechanism in which blood flows in the opposite direction to the water that flows over the fish's gills. fish gills have protrusions called lamellae which the water flows over. With the counter current exchange system the water is always richer in oxygen than in the blood therefore maintaining the concentration gradient. The oxygen then diffuses into the blood capillaries of the fish.         
19.                
    1. Centromere
       Chiasmata
    2. Non- Sister chromatids cross over and exchange genetic genis leading to variation
    3. Meiosis
    4. Testes and ovaries
       
       
20.               
    • Carbon (IV)oxide
    • Uric acid
      
      
21. Plasmodium
    
    
22.     
    • Discontinuous variation - type of variation with a definite distinct groups without intermediate forms eg tongue rollers
    • Continuous variation - variation that exhibits wide range of difference for the same characteristics height, skin colour etc.
      
      
23.  
    • DNA contains the sugar deoxyribose, while RNA contains the sugar ribose. The only difference between ribose and deoxyribose is that ribose has one more -OH group than deoxyribose, which has -H attached to the second (2') carbon in the ring.
    • DNA is a double-stranded molecule, while RNA is a single-stranded molecule.
    • DNA is stable under alkaline conditions, while RNA is not stable.
    • DNA and RNA perform different functions in humans. DNA is responsible for storing and transferring genetic information, while RNA directly codes for amino acids and acts as a messenger between DNA and ribosomes to make proteins.
    • DNA and RNA base pairing is slightly different since DNA uses the bases adenine, thymine, cytosine, and guanine; RNA uses adenine, uracil, cytosine, and guanine. Uracil differs from thymine in that it lacks a methyl group on its ring.
                   
24.           
    • Gamete formation 
    • Fertilization
    • Mutations environmental factors
      
      
25.                
    • Embryo not fully developed
    • Presence of chemical inhibitors
    • LOw concentration of growth hormones
    • Hard and impermeable seed coats
    • Absence of certain wave length
      
      
26. Fruit formation wihtout fertilization
    
    
27.                    
    • Inhibit development of side branches
    • Stimulate growth of adventious roots in stem cutting
    • Stimulates cell division and elongation leading to primary growth.
      
      
28.        
    

    Diffusion	Active transport
    Works from alevel of low concentrartion to level of high concentration	Works from level of low concentration to level of low concentration
    Does not require enzymes	Requires enzymes/ cellular energy  to occur
    Works through concentration gradient	Works against concetration gradient
    Miantains dynamic euilibrium	No equilibrium is oberved/ established thoughout the process

           
29.             
    • Long loops of henle to increase water absorption
    • reduce glomerulus
    • Reduced Bowman's capsule
      
      
30.          
    • Leaves are reduced in size other modified to spines
    • Leaf shedding
    • Reduce transpiration
    • Leaves folded
    • Leaves sunken stomata