Biology Questions and Answers - Form 2 End Term 3 Exams 2023

INSTRUCTIONS

• Write your answers correctly and clearly in the spaces provided
• Be keen on Spelling of Technical Terms

1. Name the branch of Biology that deals with the study of the following:
   1. Classification of living organisms (1mk)
   2. Internal structure of an organism (1mk)
2. Explain why an insect needs to undertake gaseous exchange    (2mks)
3. Identify and state the function of each of the following apparatus (4mks)
   
4.  
   1. Write down the formula for calculating magnification when using a light microscope to observe specimen (1mk)
   2. Sam drew the rear leg of a grasshopper which measured 45mm on the insect. If he used a magnification of X0.5, calculate the length of the leg drawn in centimeters. (3mks)
5. Use the diagram shown to answer the questions that follow
   
   1. Name the mode of feeding for the animal whose lower jaw is shown above (1mk)
   2. Give TWO reasons for your answer in a) above (2mks)
6. Account for the following observations
   1. A mountain climber has more red blood cells than a person of the same size, age and gender living in low lands (2mks)
   2. A baby has higher energy requirement than an adult (2mks)
7. The diagram shown below is of a structure found in cells
   
   1. Label the following parts: Phospholipid layer; a pore (2mks)
   2. State TWO properties of the structure above (2mks)
8.  
   1. Define the term ‘active transport’ (1mk)
   2. Give TWO ways in which active transport and diffusion are different  .(2mks)
9. State the economic importance of the following excretory products from plants (3mks)
   1. Papain: ……………………………………………………………………………………………………….
   2. Quinine: ……………………………………………………………………………………………………...
   3. Colchicine: ………………………………………………………………………………………………….
10. The following diagram is a cross section of a dicot plant
       
    1. From which organ of the plant was the cross section above obtained?   (1mk)
    2. Give a reason for your answer in a) above (1mk)
11.  
    1. How is large surface area achieved in red blood cells in order to enable them be efficient at their function. (2mks)
    2. Give TWO advantages of Carbon (IV) Oxide transportation by the red blood cells (2mks)
12. Distinguish between the following terms:
    1. Allograft and isografts (2mks
    2. Guttation and Transpiration (2mks
13.  
    1. Explain how the following antibodies defend the body against pathogens
       1. Lysins……………………(1mk)
       2. Agglutinins………………(1mk)
    2. Which other way do White Blood Cells defend the body against pathogens in addition to use of antibodies?   1mk
14.  
    1. What is the role of proximal convoluted tubule in the kidney? (1mk
    2. Give TWO adaptations of proximal convoluted tubule to its function  (2mks
15. Name the organelles that form the following: (2mks
    1. Ribosomes …………………………………………………………………………………………….
    2. Lysosomes: …………………………………………………………………………………………..
16. State THREE structural differences between arteries and veins (3mks
17. Study the diagram shown below
    
    1. State the adaptation of the organelle shown above to its function  .(1mk
    2. Name TWO products from the process that takes place in the organelle shown above which are useful in the physiological process that occurs in the chloroplast of plant cells (2mks
    3. Why do Red Blood Cells lack the organelle shown above? (1mk
18.  
    1. What is an enzyme? (1mk
    2. Give THREE factors that increase rate of enzymatic reactions (3mks
19. The table below shows the number of various teeth in the jaws of an animal
    

    	Canines	Molars	Incisors	Premolars
    Lower Jaw	2	6	4	4
    Upper Jaw	2	6	0	4

    1. Determine the total number of teeth the animal has (1mk
    2. Write down the dental formula of the animal whose teeth are shown on the table above (1mk
    3. With a reason, determine the mode of feeding of the animal represented above (2mks
       1. Mode of Feeding…………………………………………………………………………………………
       2. Reason……………………………………………………………………………………………………
20.  
    1. Label the following parts of the light microscope on the diagram shown below (4mks
       Coarse Adjustment Knob; Revolving Nose Piece; Mirror; Objective lens
       
    2. State TWO precautions observed before storage of the light microscope   (2mks
21. Consider the following experimental set up used to investigate a physiological process
    
    1. What was the aim of the experiment? (1mk
    2. Account for the change that will take place in the thermometer (2mks
    3. Suggest a control for the experiment shown above (1mk
22. Consider the following equation of a chemical equation
    
    If A is glucose and C is Lactose, Name the Following
    1. Enzyme X ………………………………………..….(1mk
    2. Compound B …………………………………………(1mk
23. The following diagram shows onions cells captured in a field of view of a light microscope.
    
    1. Measure the length of the white line to determine the diameter of the field of view in millimeters (1mk
    2. How many cells are found along the diameter represented by the white line?  (1mk
    3. Determine the actual diameter of one cell if a magnification of X1000 was used to observe the cells above (3mks
    4. State a weakness of the process above of estimating cell size (1mk)

MARKING SCHEME

1.  
   1. Taxonomy;
   2. Anatomy;
2. Supply Oxygen needed for Respiration/Oxidation of food; Expel Carbon (IV) Oxide (whose accumulation in the body will be toxic);
3.  
   1. Pitfall Trap; Trap small crawling animals;
   2. Pooter; Suck small animals on tree barks/rocks;
4.  
   1. = Eye Piece Lens Magnification X Objective Lens Magnification;
      REJ if the word ‘Magnification’ is omitted
   2. Magnification = (object length/Image length)
      Image length = Object length/Magnification)
                            = 45mm/0.5;
                            = 90mm
      But 10mm = 1cm
      Thus 90mm = (90mm X 1cm)/10mm; NB: Deny Mark if Units not shown here
      Image length = 9cm; NB: Deny Mark if Units not shown here
5.  
   1. Carnivorous;
   2. Long curved canine; Has Carnassial tooth;
6.  
   1. Increase Surface area to capture Oxygen molecules; Since higher altitudes have lower Oxygen Concentration;
   2. More Physically Active than an adult; Still Undergoing rapid growth/cell division; Larger surface area thus loses more heat energy per unit area, thus needs more to compensate for the lost one;
7.  
   1.  
      
   2. Semi-permeable/selectively permeable; polarized/has negative and positive charges; sensitive to changes in temperature/ Denatured by temperature beyond 40°C;
8.  
   1. Movement of particles against concentration gradient by use of energy;
   2.  
      

      Active Transport	Diffusion
      Molecules Move against Concentration gradient/	Molecules Move along the Concentration Gradient;
      Requires Energy/Is an Active Process	Energy Not Required/Is Passive;
      Uses Carrier Molecules	Carrier Molecules Not Required;

9.  
   1. Papain-Meat Tenderizer;
   2. Quinine-Treatment of Malaria;
   3. Colchicine-Anti-cancer therapy; Genetic Research;
10.  
    1. Root;
    2. Star-shaped Xylem; Xylem is central;
11.  
    1. Are Numerous; Biconcave Shape;
    2. pH of blood not altered; faster/efficient (due to action of enzyme carbonic anhydrase);
12.  
    1.  
       • Allograft-Graft/Organs from persons who are not genetically identical;
       • Isografts-Grafts from genetically identical twins; NB: Award at each point
    2.  
       • Guttation: Loss of Water in Liquid form/: Loss of Water in Liquid form through hydathodes
       • Transpiration: Loss of water vapour/Loss of water vapour via Stomata/Lenticels/Pneumatophore; NB: Award at each point
13.  
    1.  
       1. Lysins: Digest Cell membranes or Cell wall of pathogens;
       2. Agglutinins: Clump pathogens together thus stops them from multiplication/ ease ingestion of pathogens by phagocytes;
    2. Phagocytosis/Being Ingested/Engulfed (by Granulocytes/Monocytes);
14.  
    1. Selective reabsorption of nutrients;
    2. Long to increase surface area for reabsorption of nutrients; Highly coiled to slow down movement of renal fluids for efficient reabsorption; Numerous micro-villi to increase surface area for reabsorption of nutrients; Numerous mitochondria to supply enough energy for reabsorption of nutrients; thin inner lining to a offer a shorter distance for faster diffusion of nutrients into the blood stream; Mark 1st TWO
15.  
    1. Nucleolus; 
    2. Golgi apparatus/Golgi bodies;
16.  
    

    ARTERY	VEIN
    Narrow Lumen	Wider Lumen;
    Thick Muscular and Elastic Wall	Thin Less Muscular and inelastic Wall;
    Lack Valves along its length	Have Veins along its length;

17.  
    1. Highly folded inner membrane/Has cristae to increase surface area for attachment of more respiratory enzymes;
    2. Energy/Adenosine Triphosphate; Carbon (IV) Oxide;
    3. Prevent Oxygen utilization thus increase efficiency in Oxygen transport;
18.  
    1. It is a Bio-catalyst/Catalyzes/Increases rate of metabolic reactions;
    2. Optimum temperature; Optimum pH; Higher Enzyme Concentration; Higher Concentration of Enzyme co-factors/co-enzymes; Lack of/Lower concentration of Inhibitors; Lower Concentration of Substrate; Mark 1st 3
19.  
    1. Total Number of Teeth = (2+2+6+6+4+4+4) = 28;
    2. i 0 c 1 pm 2 m 3 ; REJ: Capital letters; Lack of Fractions
         2    1       2     3
    3. Herbivorous; Lack incisors in the upper jaw; REJ: Has Horny pad;
20.  
    1.  
       
    2. Clean lenses with a soft lens tissue; Clean other parts using a soft cloth/tissue paper; Click the Low Power Objective Lens into Position; Store in a cabinet away from dust;   Mark 1st 2
21.  
    1. To find out if heat energy is released during respiration;
    2. Increase in temperature recorded by the thermometer; since yeast beaks glucose through respiration to release heat;
    3. Same set up but without yeast;
22.  
    1. Lactase;
    2. Galactose;
23.  
    1. 62mm;
    2. 6 (cells);
    3. Observed Diameter of Cell = Diameter of Field of View/Number of cells
                                                   = 62mm/6cells
                                                   = 10.33mm; NB: Deny Mark if Units not shown here
       Actual Diameter of 1 cell = Diameter of Observed cell/Total Magnification
                                               = 10.33mm/1000; NB: Deny Mark if Units not shown here
                                               = 0.0103mm; NB: Deny Mark if Units not shown here
    4. Cells are not linearly/uniformly arranged along the diameter of field of vies; Cells are of different Size; Cells are of different Shapes;