Biology Paper 2 Questions and Answers - Mumias West Pre Mocks 2022

QUESTIONS

SECTION A (40 MARKS)
Answer all the questions in this section in the spaces provided:

1. The diagram below illustrates the structure of the kidney nephron.
   
   
   1. Name the part labeled E. (1 mark)
   2. How is the part labeled F adapted to its function? (4 marks)
   3. State three physiological mechanisms of controlling the human body temperature during a cold day. (3 marks)
2. The genetic disorder hemophilia is due to a recessive sex linked gene .A man who is hemophilic marries a woman who is carrier for the condition.
   
   1. Using letter H to represent the gene normal condition and letter h for the gene for hemophiliac condition.
      
      1. What is the genotype for the man and the woman? (2marks)
      2. Work out a cross between the man and woman (3marks)
   2. What is the chance that both the first and second sons will be hemophiliac? (2marks)
   3. Hemophilia is more common in males than in female humans. Explain (1mark)
3. The diagram below represents a state in cell division. Study it and answer the questions below.
   
   
   1. Name the stage of cell division illustrated in the diagram above. (1 mark)
   2. Name the parts labelled A, B and C (3 marks)
   3. State THREE differences between mitosis and meiosis. (3 marks)
   4. Name the process during which the exchange of genetic materials occur at prophase 1 of meiosis. (1 mark)
4. The diagram below indicates an organism that grows under shaded places with damp conditions. Study it and answer the questions that follow.
   
   
   1. Name the division to which the specimen belongs. (1 mark)
   2. Name and state the functions of the parts labeled Q, R and S. (6 marks)
   3. Name the two body forms of the organism in its alternation of generation. (2 marks)
5.      
   1. Explain how the following meristematic tissues contribute to growth of higher plants
      
      1. Vascular cambium (2marks)
      2. Cork Cambium (2marks)
   2. The diagram below shows a life cycle of a cockroach
      
      Name the hormone that would be at high concentration during.
      1. First week (1mark)
      2. Second week (1mark)
   3. Name the structure that produces hormone in a (ii) above (1 marks)
   4. Name the series of stages through which the nymph undergoes to reach adult stage (1 marks)

SECTION B:(40 MARKS)
Answer question 6 (Compulsory) and EITHER question 7 or 8 in the spaces provided after question 8.

6. An experiment was carried out in which red blood cells were put in salt solutions of different concentrations. The table below shows the percentage of cells which were destroyed by haemolysis in different salt concentration.
   

   Salt concentration (g/dm³)	% of RBC destroyed By haemolysis
   0	100
   1	100
   2	100
   2.5	100
   3.0	100
   3.5	96
   3.7	80
   4.0	60
   4.5	16
   4.7	0
   5.0	0
   6.0	0

   1. Draw a graph of percentage of red blood cells haemolysed against salt concentration. (6 marks)
   2. Explain haemolysis of red blood cells. (3 marks)
   3. From the graph, state:
      1. the salt concentration at which 50% red blood cells were haemolysed. (1 mark)
      2. the highest salt concentration when the largest number of red blood cells were haemolysed. (1 mark)
   4.      
      1. Suggest the normal salt concentration in the blood of the mammal from which the red blood cells were obtained. (2 marks)
      2. Give a reason for your answer in (d) (i) above. (1 mark)
      3. What term is used to describe the solution with equal solute concentration as that of the cells? (1 mark)
   5. Name the process in the human body that ensures that haemolysis of red blood cells is prevented. (1 mark)
   6. State four roles of osmosis in organisms. (4 marks)
7. Describe the role of hormones in the mammalian female reproductive cycle. (20 marks)
8. Describe the
   1. Process of inhalation in mammals (10 marks)
   2. Mechanism of opening and closing of stomata (10 marks)

MARKING SCHEME

1.        
   1. Glomerulus; rej. glomeruli 1mk
   2. It is long to increase the surface area for re absorption of water
      It is lined with a network of blood capillaries to enhance re absorption of water
      It is un-shaped to bring about a counter multiplier effect/to concentrate salt in the medulla to bring about re-absorption of water
   3. Vasoconstriction
      Hair rises Acc pilo erection for hair rising
      Metabolic rate increases
      Shivering
2.    
   1.      
      1. Man
         Xhy; (2 marks)
         Woman
         XHXh ;
      2. Parental genotype
         XHXh X Xh y;
         
   2. ¼ x ¼; = 1/16 (2 marks)
   3. y chromosomes does not have the corresponding allele for the gene that determine or cause haemophilia/y chromosome
      is almost genetically empty; (1 mark)
3.      
   1. Metaphase of meiosis1;
   2. A - Cell membrane;
      B - Spindle fibre;
      C - Centriole;
   3. 
      

      Mitosis	Meiosis
      (i) Occurs in all somatic cells	Occurs only in reproductive cells;
      (ii) Occurs in one phase	Occurs in 2 phases;
      (iii) Daughter cells produced are diploid	Daughter cells produced are haploid;
      (iv) Homologous chromosomes do not come together/do not pair	Homologous chromosomes come together/pair;
      (v) No variation at the end	Variation occurs at the end;

      (Any first 3 @ 1 Mark = 3 Marks)
   4. Crossing over;
4.         
   1. Pteridophyta
   2. Q
      Name - Adventitious root; (reject roots)
      Function - Anchorage/absorption of water
      R
      Name - Rhizome (underground stem)
      Function - For storage of food and water
      S
      Name - Sorus
      Function - Contains (Sporangium with a sexually reproductive)spores
   3. Name the two body forms of the organism in its alternation of generation. (2 marks)
      Gametophyte
      Sporophyte
5.      
   1.           
      1. Vascular cambium ;
         Found between the xylem and phloem of woody plants; cells decide to give rise to secondary xylem and phloem; resulting to increase in birth / Diametre ; secondary parenchyma ; is formed between adjacent vascular bundles resulting to secondary growth
      2. Cork Cambium ;
         Located beneath the Epidermis; Divides to form secondary cortex ; and corky cells ; ( to the inside and outside respectively Preventing rapturing of the stem and root when vascular cambium increase in firth
   2.      
      1. Juvenile hormone (1mk)
      2. Ecdysone / moulting hormone (1mk)
      3. Prothoracic gland (1mk)
      4. Instar (1mk)
6.        
   1. On the graph.
      
   2. Haemolysis of red blood cells occurs when they are placed in a hypotonic solution; they gain a lot of water; swell an then burst; (3 mks)
   3. 4.1 g/dm³; + 0.1; (1 mk)
      3.0 g/dm³; + 1; (1 mk)
   4.    
      1. 4.7 g / dm³+ 0.1; (1 mk)
      2. At 4.7 g / dm³ salt concentration; as there is no haemolysis / haemolysis was zero; (2 mks)
      3. Isotonic solution; (1 mk)
   5. Osmoregulation; Rej. homeostasis (1 mk)
   6. Osmosis enables movement of water from one cell to another;
      Osmosis helps in closing and opening of the stomata;
      Osmosis helps in support when cells become turgid in plants;
      Osmosis helps in absorption of water by the root hairs; (max 4)
7. Follicle stimulating hormone (FHS); is secreted from the anterior lobe of the pituitary gland just after menstruation; It causes Graafian follicle to grow in the ovary; FSH also stimulates tissues of the ovary to produce oestrogen;
   Oestrogen; brings about healing and repair of endometrium; destroyed during menstruation; Accumulation of oestrogen; stimulates pituitary gland produce Luteinising hormone (LH);
   Luteinising hormone (LH); stimulates maturation of graafian follicle; The manure graafian
   follicle releases an ovum into funnel shaped part of the ovary; This is known as ovulation;
   LH also brings about changing of graafian follicle into corpus luteum; LH then stimulates corpus luteum to secrete progesterone;
   Progesterone; stimulates thickening of the endometrium and increases blood supply to the endometrium; in preparation for implantation. When fertilisation has taken place, progesterone
   levels increase and this inhibits secretion of FSH; hence no more growth of graafian follicle;TOTAL 22 MAX 20
8.      
   1. Process of inhalation in mammals
      
      • External intercostals muscles contract; while internal intercostals muscles relax;
      • (This movement) pulls ribs upwards and outwards;
      • The diaphragm muscles contract; and the diaphragm flattens;
      • (All the above movements) increases the volume of thoracic cavity; and decreases its pressure; Atmospheric pressure being higher than thoracic cavity pressure; Forces the air to rush into the lungs; (through the nose and trachea)
      • The lungs are inflated;. (Max. 10 Marks)
   2. During the day, chloroplast of guard cells accumulate sugar/glucose produced through the process of photosynthesis;
      
      • Accumulated sugar/glucose in the guard cells increases osmotic pressure of the cell sap of the guard cells;
      • Water is drawn from the neighbouring epidermal cells by osmosis;
      • Guard cells become turgid and bulges outward;
      • This opens the stomata;
      • At night, sugar/glucose which had accumulated in guard cells is converted to starch;
      • Osmotic pressure of guard cells falls;
      • The cells lose water to the neighbouring epidermal cells and become flaccid;
      • The guard cells are drawn towards one another;
      • The stomata closes; (Max 10 Marks)