Biology Paper 2 Questions and Answers - Mincks Group of Schools Mock Examinations 2022

INSTRUCTIONS TO CANDIDATES

• Write your name, class and admission number in the spaces provided above.
• Answer all questions in the spaces provided.
• This paper consists of Question 1 to 8
• Answer all questions in section A. Question 6 is compulsory, then choose either question 7 or 8.
• Students should check the question paper to ascertain that all the pages are printed as indicated and no questions are missing.

FOR EXAMINER’S USE ONLY

QUESTIONS

SECTION A - 40 MARKS

1.                    
   1. What is meant by the term Genetics. (1mk)
   2. State two examples of discontinuous variation in human beings. (2mks)
   3. A female with sickle cell trait marries a normal man. The allele for Sickle cell is Hbs and the normal allele HbA. Determine the probability that their first born will have sickle cell trait. Show your working. (5mks)
2. Study the diagram below of the mammalian ear and answer the questions that follow.
   
   
   1. Name the parts labeled X,Y and N. (3mks)
      X
      Y
      N
   2. State how the parts labeled Y are adapted to their functions. (2mks)
   3.                        
      1. Besides hearing, state one other function of the ear. (1mk)
      2. Which of the labeled parts is responsible for the function you have stated in c(i) above. (1mk)
   4. What would happen if the auditory nerve is completely damaged? (1mk)
3. The diagram below represents a stage of growth in a seed during germination.
   
   
   1.                      
      1. Name the type of germination illustrated above. (1mk)
      2. Give a reason for your answer in a(i) above. (1mk)
   2. Name the part labeled R. (1mk)
   3. Give two functions of the part labeled Q. (2mks)
   4. Explain how part labeled P straightens. (3mks)
4. Below is a diagram of structure found in Eukoryotic cells. Study it and answer the questions that follows.
   
   
   1. Identify the structure. (1mk)
   2. State two functions of the structure. (2mks)
   3.                  
      1. Name one organelle found in animal cells but absent in plant cell. (1mk)
      2. State one function of the organelle you have named in c(i) above. (1mk)
   4. State 3 properties of structure you have identified in (a) above. (3mks)
5. The diagrams below represents a set up to investigate the conditions necessary for seed germination.
   
   The set up was left for 7 days.
   1. What conditions were being investigated in the experiment? (2mks)
   2. State three reasons for soaking seeds in set up A and B. (3mks)
   3. What were the expected results after seven days. (3mks)
      1. Set up A
      2. Set up B
      3. Set up C
6. The table below shows how quantities of sweat and urine vary with external temperatures.
   

   External Temperature oC	Urine (cm3/hr)	Sweat cm3/hr
   0	100	5
   5	90	6
   10	80	10
   15	70	20
   20	60	30
   25	50	60
   30	40	120
   35	30	200

   1. Using the same axis, draw a graph of quantity of urine and sweat against the external temperature. (7mks)
   2.                  
      1. State the quantity of urine and sweat produced when external temperature was 12.5ºC. (2mks)
      2. State the physical process through which the body was cooled by sweating as temperature was rising. (1mk)
      3. Account for the quantity of urine produced as the temperature increased. (4mks)
   3. State the nitrogenous waste that could be eliminated in urine or sweat in human beings. (3mks)
   4. State three behavioural mechanism that poikilotherms use to regulate their body temperature under hot conditions. (3mks)
7.                    
   1. Describe the process of double fertilization in flowering plants. (14mks)
   2. State the changes that occur in a flower after fertilization. (6mks)
8.                    
   1. State the importance of locomotion in animals. (4mks)
   2. Describe the adaptations of the finned fish to locomotion. (16mks)

MARKING SCHEME

1.                                          
   1. Genetics – Branch of biology that deals with the study of inheritance and variation. (1mk)
   2.                        
      • sex
      • ABO blood group
      • Toungue rolling
      • free or attached earlobe
      • Hairs in ear pinna / nose (2mks)
   3.                                        
      
      

      Male / Female	HbA	HbA
      HbA	HbAHbA	HbAHbA
      Hbs	HbAHbs	HbAHbs

      Probability of sickle cell trait (Hb^AHb^s)
      2⁄4 = ½; 0.5; 50%; (5mks)
2.                      
   1. X – External auditory meatus;
      Y – Ear ossicles;
      N – Eustachian tube;
   2. They are bony/solid and small forming a lever system that amplifies and transmits vibrations to the fenestra ovalis.
      They are loosely held by suspensory ligaments which enables them to transmit vibrations;
      NB: Mark any one.
   3.                          
      1. Maintaining body balance / posture;
      2. M; NB: (ii) is tied to (i)
   4. Permanent deafness; rej. Deafness alone
      lack of balance Mark any one
3.                          
   1.                      
      1. Epigeal germination; (1mk)
      2. Hypocotyl grows faster pulling the cotyledons above the ground; (1mk)
   2. Seed coat; (1mk)
   3.                      
      • protect the embryo; (1mk)
      • food storage; (1mk)
   4. Exposure of the curved part to light stimulates migration of auxin to the lower side; higher concentration of auxin on the lower side stimulates faster cell elongation; on the lower side than on the upper side; and this causes P to straighten. (3mks)
4.                  
   1. Cell membrane;
   2.                    
      1. It encloses cell contents;
      2. It selectively allows materials in and out of the cell;
   3.                    
      1. Centriole;
      2. Take part in formation of cilia and flagella.
         Take part in formation of spindle fibres during cell division
   4.              
      • Sensitive to changes in temperature and pH
      • Posses electric charges / polarized
      • Semi-permeability
5.                          
   1. Water; acc moisture
      Temperature; acc warmth (2mks)
   2. Mobilise / Activate enzymes / hydrolyse stored food / breaking of dormancy;
      softens the testa / seed coat;
      acts as a solvent / medium of transport; (3mks)
   3.                      
      1. Those in set up A will geminate; (1mk)
      2. Those in set up B will not geminate; (1mk)
      3. Those in set up C will not germinate; (1mk)
6.                      
   1. On graph paper. (7mks)
   2.                    
      1. Urine 74 cm3 / hr ± 1
         Sweat 14cm3 / hr ±1 (2mks)
      2. Evaporation (1mk)
      3. An increase in external temperature decreases the amount of urine produced; this is due to increased sweating; which increases osmotic pressure of blood; hence more water is reabsorbed back into the blood stream at the kidney tubules. (4mks)
   3. Urea
      • Uric acid (3mks)
      • Ammonia
   4.                    
      • Aestivation
      • Staying under shaded places. (3mks)
      • Borrowing underground.
7.                    
   1.                          
      • pollen grains land and stick onto the stigma; stigma secretes / produces a sticky fluid; that causes pollen grains to adhere onto it.
      • Sticky secretion also stimulates the pollen grain to germinate; into a pollen tube;
      • The pollen tube grows into the stigma and protrudes down the style tissues;
      • The pollen tube denies its nutrition from style tissues
      • As the tube grows downwards, the tube nucleus occupies the position just behind the tip;
      • The generative nucleus then enters the tube and divides mitotically; to give a pair of male gamete nuclei; which follow the tube nucleus and the pollen tube grows further doen the style.
      • On reaching the ovary, the pollen tube enters the ovule through the microphle;
      • It bursts open;
      • The vegetative (tube) nucleus disintegrates; leaving a clear passage for the two male gamete nuclei.
      • One male gamete fuses with the functional egg cell; to form a diploid zygote;
      • The other fuses with the two polar nuclei; to form a triploid nucleus; called primary endosperm nucleus;
   2.                  
      • Zygote (divides mitotically) and forms the embryo; Embryo differentiates into plumule and radicle; primary endosperm nucleus (divides mitotically) and becomes the endosperm (for food storage);
      • integuments become the seed coat;
      • antipodal nuclei and synergids disintegrate;
      • ovules become seeds;
      • ovary wall becomes the pericarp;
      • stigma and style dry up leaving a scar;
      • corolla dries up;
      • calyx may dry up or persist;
8.          
   1.                                       
      • Searching for food / mates / shelter, (4mks)
      • Migration away from unfavourable conditions/ environments;
      • Escape from predators / enemies;
      • Colonization of new areas;
   2.                                
      • Vertebral column consists of a series of vertebrae; held together loosely so that its flexible;
      • Myotomes / muscles; associated with vertebral column contract and relax to produce movement;
      • The sideways and backwards thrust of the tail and body against water, result in resistance of the water pushing the fish sideways;
      • Head is inflexible; to maintain the forward thrust;
      • Body streamlined; to reduce resistance;
      • Presence of fins; for forward movement / balance in water;
      • Presence of swim bladder; make fish buoyant;
      • Scales tip towards the back; provide smooth surface to reduce resistance (friction);
      • Body covered with mucus making it slippery; hence reducing friction during movement in water.
        18 marks, max 16 marks