Biology Paper 2 Questions and Answers - Maranda Pre-Mock Examinations 2022

QUESTIONS

1. In an experiment to investigate a certain aspect of photosynthesis, two leaves Q and P from a de-starched potted plant were treated as shown on the diagram below.
   
   The plant was then placed in an open field for three hours after which a certain test was carried out on the two leaves to find out if photosynthesis had taken place.
   1.      
      1. Which aspect of photosynthesis was being investigated? (1mark)
      2. How was the potted plant de-starched? (1mark)
   2.      
      1. What test was carried out to tell whether photosynthesis has occurred? (1mark)
      2. Account for the expected result when the test named in b(i) above was carried out on leaves Q and P. (4marks)
   3. Suppose in the set up Sodium hydroxide pellets were replaced with Sodium hydrogen carbonate in the flask with leaf P. Explain the result of the same test on the leaf P.
2. The diagram below represents cells of a tissue and associated circulatory vessels.
   
   
   1. Name the fluid that filters from the capillary into space A (1mark)
   2.    
      1. Name two substances that the cells obtain from the fluid in space A.
      2. Name two components of blood that do not filter into space A.
   3.      
      1. Name the fluid in vessel B.
      2. State two differences in composition between blood in arteriole and that in venule. (2marks)
         

         Arteriole	Venule

3. The diagram below shows a root system from a certain plant
   
   
   1.      
      1. Name structure Q (1mark)
      2. Explain briefly the significance of having structures Q in the root system of the plant represented above. (4marks)
   2. What mode of nutrition is demonstrated in the diagram? (1mark)
   3. With a reason, state the class to which the plant represented in the diagram belong? (2mark)
      Class
      Reason
4. A student set up the following apparatus using socked been seeds and boiled been seeds to investigate a certain biological phenomenon.
   
   
   1. What is the aim of the experiment?
   2. State the expected observations after 3 days.(2marks)
   3. Account for the observations made after 3 days. (2 marks)
      Flask A
      Flask B
   4. Why was it important to wash the dead seeds with antiseptic? (2 marks)
   5. What is the purpose of set up B?
5. A baby has blood group B while the mother's blood group is A. The paternal grandfather is blood group B and the paternal grandmother is blood group A.
   1. Determine the genotypes of the baby's: - (4marks)
      1. Paternal grandfather 
      2. Paternal grandmother
      3. Father
      4. Mother
   2. If the mother and father have non-identical twins, what is the probability that both children will have blood group B? Show your working. (4marks)
      
6. In a certain school invaded by mosquitoes and cockroaches, students collected a data on the population of each species over a period of two weeks. The results are tabulated below.
   

   DAY	1	3	6	9	12	15
   Number of mosquitoes	35	60	130	210	260	250
   Number of cockroaches	20	40	56	70	75	80

   1. On the same axes plot the graphs of the two populations against time. (7marks)
   2. State the most suitable equipment to collect each of the species: (2 marks)
      1. Cockroaches
      2. Mosquitoes (4marks)
   3. Account for the shape of the curve for the mosquitoes between:
      1. 1st and 3rd day
      2. 12th and 15th day
   4. Mosquitoes are vectors of a certain parasite.
      1. Name the parasite. (1mark)
      2. Name the disease caused by the parasite named in d(i) above. (1mark)
   5. Explain:
      1. One way that makes cockroaches better adapted in the environment than the mosquito. (1mark)
      2. Why the population of mosquitoes is not affected by the population of the cockroaches. (1mark)
7. Describe the nitrogen cycle. (20 mks)
8.      
   1. Define a reflex arc (2 mks)
   2. A young boy accidentally touched a sharp pin. He suddenly gave a shout and withdrew the hand from the pin. Describe the activities that led to withdrawal of the hand from the pin. (18 mks)

MARKING SCHEME

1.      
   1.      
      1. Necessity of carbon(iv) oxide in photosynthesis
      2. placing the potted plant in darkness for 48hrs 
   2.    
      1. starch test/ iodine test
      2. leaf Q starch was present ; this is because there was carbon (iv) oxide gas inside the flask hence photosynthesis occurred with formation of starch;
         leaf pv starch would be absent; sodium hydroxide inside the flask would absorb carbon (iv) oxide inside the flask hence no photosynthesis would take place
   3. starch would be present/leaf would turn blue/black; because NaHCO₃ would decompose releasing CO₂ which is used by leaf to photosynthesize
2.    
   1. tissue fluid/intercellular fluids
   2.      
      1. oxygen
         nutrients/ glucose/ amino acids
      2. plasma proteins
         blood cells/ red blood cells/ platelets
   3.      
      1. Lymph
      2.      
         

         Arteriole	Venule
         has more oxygen has less carbon(iv) oxide has more nutrients has less metabolic wastes	has less oxygen; has more carbon(iv)oxide has less nutrients has more metabolic wastes

3.      
   1.      
      1. roof nodule
      2. Q contains large number of bacteria that fix free nitrogen from atmosphere into nitrates/ a form that can be utilized by by the plant
   2. symbiosis
   3. Class - dicotyledone
      Reason - has fibres root system
4.      
   1. to investigate the release of heat energy in germinating seeds
   2. A:hermometere reading increased
      B:Thermometer reading remains the same
   3. A - germinating seeds respired releasing heat
      B - Boiling killed the embryo of the seeds hence they don't respire
   4. to kill all micro-organisms/decomposers; since they may respire releasing heat which may cause a rise in temperature
   5. control experiment
5.      
   1.      
      1. BO/BB
      2. AO
      3. BO/AB
      4. AO
   2.   
      
6.      
   1.    
      
      
   2.    
      1. pitfall trap
      2. sweep net
   3.      
      1. the pop of mosquitoes increases slowly; becasue they had not adjusted to the environment; there were fewer reproducing mosquitoes
      2. the pop of mosquitoes decreased/ gradually; because carrying capacity has been outstretched/resources have become limited e.g food, space
   4.    
      1. plasmodium(any correct normal species)
      2. malaria
   5.    
      1. they camouflage well with the background
         they feed on a variety of plant materials
         flattened body to enable them to hide in crevices against predation
      2. they belong to different species and occupy different niches hence do not compete for resources
7. the nitrogen cycle:
   during thunderstorms/lightning nitrogen gas combines with oxygen to form nitrogen oxides which dissolve in water to form nitric acid. the acid is deposited in the soil by rain. nitric acid combines with chemical substances in the soil to form nitrates/dissociates to form nitrates which are absorbed by plants.
   symbiolic bacteria found in the root nodules of leguminous plants; fix free nitrogen to nitrogen. free living bacteria; fix nitrogen to nitrates; free living organisms/ algae/ chlorella; fix nitrogen to nitrates; plants/animals die and decomposed by bacteria/fungi; thereby releasing ammonia; which is converted into nitrites by nitrosamines bacteria; the nitrites are converted into nitrates; by nitrobacteria; nitrates in the soil can be converted to free nitrogen/ denitrification by some fungi;/ other dentrififying bacteria;
8.     
   1. it is the route followed by the nerve impulse from the receptor to the effector
   2. when the pin is touched, pain receprots in the skin are stimulated and an impulse is generated. the impulses are transmitted along the sensory neuron to the grew matter of the spinal chord through the dorsal root
      the impulse is then trasmitted to the relay/intermediate neuron through a synapse. the impulse is integrated and is then transmitted to the motor neurone and through another synapse. the motor neurone found in the ventral root transmits the impulses to the effector muscle of the hand(biceps) which responds by contracting.
      At the same time, the triceps muscle relaxes and the hand folds with drawing from the sharp pin.