Biology Paper 3 Questions and Answers With Confidential - Wahundura Boys Mock Examination 2023

INSTRUCTIONS

• This paper contains THREE Sections. Answer ALL the questions in the spaces provided IN THIS PAPER.
• ALL the answers must be clear and precise.
• Answer all the questions using correct English.

QUESTIONS

1. You are provided with specimens labeled Q and R. Study them carefully and answer the questions that follow.
   1. Name the specimens Q and R. (2 marks)
      1. Q ………………………………………………………………………………..
      2. R ………………………………………………………………………………..
   2. Identify the joints formed by R in its proximal and distal ends. (2 marks)
      1. Proximal end ……………………………………………………………………
      2. Distal end ……………………………………………………………………….
   3. Name the substance inside the living tissue of R and state its function. (2 marks)
      1. Substance ……………………………………………………………………….
      2. Function ………………………………………………………………………...
   4. Which muscle is attached to the front of R and what is its function? (2 marks)
      1.  Muscle ………………………………………………………………………….
      2. Function ………………………………………………………………………...
   5. Draw a well-labeled diagram of specimen Q. (3 marks)
   6. The photograph below is of a certain bone in vertebrates. Study it and answer the following question.
      
      
      1. Calculate the magnification of the photograph given that the distance between s and t as measured by the ruler shown is the actual measurement of the specimen. (3 marks)
2. You are provided with a solution labeled S, a dropper, an empty beaker/Petri dish, a scalpel, visking tubing, two pieces of thread, and iodine solution in a beaker. Follow the procedure below and answer the questions that follow.
   1. Wet the visking tubing over running water to soften it and make it easy to open.
   2. Tightly tie one end of the visking tubing.
   3. Using a dropper, put solution S into the visking tubing to about three-quarters full. Ensure there is no spillage on the visking tubing.
   4. Tie the other end of visking tubing tightly. Ensure no end is leaking.
   5. Clean the surface of the visking tubing over running water to remove any traces of solution S.
   6. Place the visking tubing with solution S into the beaker with iodine solution and leave the set up undisturbed for 30 minutes.
   7. Then remove the visking tubing from the beaker, cut it and empty the contents into the empty beaker (or Petri dish)
      1. Record your observations in the table below; (4 marks)
         

         	Solution S	Iodine solution
         At the start
         At the end

      2. State the physiological process under investigation in the experiment. (1 mark)
      3. Account for the observations made in (a) above. (5 marks)
      4. Give two functions of the process named in (b) above in animals. (2 marks)
3.  Below are photographs of specimens of different types of fruits. Observe them carefully to answer the questions that follow.
    
   
   
   1. Complete the table below by indicating modes of dispersal of seeds for specimen A, C, and D and one feature that adapts each to its mode of dispersal. (6 marks)
      

      Specimen	Mode of dispersal	Adaptive features
      A
      C
      D

      
      Specimen Mode of dispersal Adaptive features
   2. Specimens D and F are both dehiscent fruits. State a difference in their mode of dehiscence. (1 mark)
   3. Name the type of fruits of photographs A and B. Give a reason for your answer in each case. (4 marks)
      

      Specimen	Type of fruit	Reason
      A
      B

      
      Specimen Type of fruit Reason
   4. Explain the advantage that the mode of dispersal of E has over that of D. (2 marks)
   5. Differentiate between the placentation of B and D. (1 mark)

CONFIDENTIAL

This document is meant to allow the Principal and the Teacher of Biology to adequately prepare for the end-of-term 2, 2023 examinations for form four 231/3, Biology practical by guiding them on materials and equipment to be acquired for the same. It is confidential and its access to unauthorized persons including but not limited to students is prohibited either directly or indirectly.
REQUIREMENTS
Together with other Biology laboratory fittings, each student should have;

1. Two specimens labeled (or have adequate access to these specimen)
   1. Specimen labeled Q
   2. Specimen labeled R
2. 5ml Solution S
3. 30 ml Iodine solution in a beaker
4. 5cm Visking tubing
5. Two pieces of thread
6. A dropper
7. An empty beaker or Petri dish
8. A scalpel

NOTE TO THE TEACHER

1.  
   1. Specimen Q (Scapula)
   2. Specimen R (Humerus)
2. Solution S is prepared by dissolving 10g starch soluble per 100cm3 distilled water.
   Prepare enough solutions for the number of your Biology students sitting for the exam.

MARKING SCHEME

1. You are provided with specimens labeled Q and R. Study them carefully and answer the questions that follow.
   1. Name the specimens Q and R. (2 marks)
      1. Q: Scapula; Rej: Wrong spelling (Spatula). Acc: Shoulder blade.
      2. R: Humerus; Rej: Humorous/Humerous/Humeras
   2. Identify the joints formed by R in its proximal and distal ends. (2 marks)
      1. Proximal end: Ball and socket joint; Rej: Shoulder joint/ball joint and socket joint/ball joint socket/ball socket
      2. Distal end: Hinge joint;
   3. Name the substance inside the living tissue of R and state its function. (2 marks)
      1. Substance: Bone marrow; ii. Function: Synthesis/manufacture/formation of red blood cells
         (erythrocytes); platelets (thrombocytes); white blood cells (leucocytes);
         Rej: Synthesis (OWTTE) of blood elements
   4. Which muscle is attached to the front of R and what is its function? (2 marks)
      1. Muscle: Biceps; Rej: Bisceps/Bicepts ii. Function: Contracts and relaxes the lower arm; or contracts to move the lower arm upwards (flex/bend the arm); or relaxes to move the lower arm downwards (extend/straighten/stretch the arm)
         Rej: ………..to move the arm (if lower is no mentioned)/hand
   5. Draw a well-labeled diagram of specimen Q. (3 marks)
      
      1 mark for diagram and 2 marks for ANY TWO correctly labeled parts.
      All lines must be continuous and no shading to score for the diagram.
      No arrows or broken label lines to score for labels. Label lines MUST touch the intended structure and no single structure should bear TWO different names.
   6. The photograph below is of a certain bone in vertebrates. Study it and answer the following question.
      1. Calculate the magnification of the photograph given that the distance between s and t as measured by the ruler shown is the actual measurement of the specimen. (3 marks)
         Magnification = ^{Length of drawing}/ _{Length of actual object}
         = ^{11.2cm (from s to t)}/ _5.6cm
         = X2
         (N.B: If dimensions change due to transition and printing errors, adjust accordingly)
2. You are provided with a solution labeled S, a dropper, an empty beaker/Petri dish, a scalpel, visking tubing, two pieces of thread, and iodine solution in a beaker. Follow the procedure below and answer the questions that follow.
   1. Wet the visking tubing over running water to soften it and make it easy to open.
   2. Tightly tie one end of the visking tubing.
   3. Using a dropper, put solution S into the visking tubing to about three-quarters full. Ensure there is no spillage on the visking tubing.
   4. Tie the other end of visking tubing tightly. Ensure no end is leaking.
   5. Clean the surface of the visking tubing over running water to remove any traces of solution S.
   6. Place the visking tubing with solution S into the beaker with iodine solution and leave the set up undisturbed for 30 minutes.
   7. Then remove the visking tubing from the beaker, cut it and empty the contents into the empty beaker (or Petri dish)
      1. Record your observations in the table below; (4 marks)
         

         	Solution S	Iodine solution
         At the start	White (Color)	Brown; Color of iodine solution Acc: color of iodine
         At the end	Blue-black;  Acc: Blueblack/Blue black Rej: Blue/black;blue or black (only); dark blue;	Brown; Color of iodine solution Acc: color of iodine

      2.  State the physiological process under investigation in the experiment. (1 mark)
         Diffusion
      3. Account for the observations made in (a) above. (5 marks)
         The visking tubing is semipermeable; it allows iodine molecules to move in/across; (because they are small). They react with starch molecules to form blue-black color; (in the visking tubing). Starch molecules are large and do not move across; hence the iodine solution remain brown/retain its color;
      4. Give two functions of the process named in (b) above in animals. (2 marks)
         1. Absorption of digested food in the ileum into blood stream;
         2. Gaseous exchange across respiratory surfaces;
         3. Excretion of nitrogenous wastes/metabolic wastes across excretory surfaces; Mark the first two
3. Below are photographs of specimens of different types of fruits. Observe them carefully to answer the questions that follow.
   1. Complete the table below by indicating modes of dispersal of seeds for specimen A, C, andand D and one feature that adapts each to its mode of dispersal. (6 marks)
       

      Specimen	Mode of dispersal	Adaptive features
      A	Animal;	Has hooks/calyx developed into hooks to attach to the animal’s body/fur/clothes/hair;
      C	Wind;	Has hair-like projections/structures/parachute of hairs (acc: floss) to float in air; Rej: wing-like structures (OWTTE)
      D	Self-dispersal; or Explosive mechanism; Rej: Selfexplosive mechanism/censor mechanism/self/ selfie-dispersal.	Has lines of weakness/sutures on the pod ovary/fruit wall that burst open violently to throw away/disperse seeds;

   2. Specimens D and F are both dehiscent fruits. State a difference in their mode of dehiscence. (1 mark)
      Specimen D dehisces along two lines while specimen F dehisces along more than two lines (to release seeds).
   3. Name the type of fruits of photographs A and B. Give reason for your answer in each case. (4 marks)
      

      Specimen	Type of fruit	Reason
      A	Cypsela;	One seeded fruit; Calyx persisted to form hooks; (for dispersal) Any ONE (Not necessarily the first)
      B	Berry;	Many seeded fruit/has many/numerous seeds; (attached/embedded in a succulent endocarp)

   4. Explain the advantage that the mode of dispersal of E has over that of D. (2 marks) Fruit/Seeds of E are dispersed over a long distance than D; reducing intra-specific competition for E;
   5.  Differentiate between the placentation of B and D. (1 mark)
      B has an axile (rej: exile/axle)/central placentation while placentation for D is marginal; (acc: linear)