Biology Paper 1 Questions and Answers - Cekana Mock Exams 2023

INSTRUCTIONS 
3. Answer all questions in the spaces provided
4. Mathematical tables and silent electronic calculators may be used
5. All working must be clearly shown where necessary

QUESTIONS

1. State the name given to the study of: (2marks)
   1. Chemical changes in living organisms.
   2.  Insects.
2. State the category of variation into which the following traits fall. (2marks)
   1. 1. Skin pigmentation.
      2. Blood group .
   2. Give two possible genotypes of blood group A. (2marks)
3. Give two differences between scientific names and common names. (2marks)
   

   Scientific Names	Common Names

4. Explain two adaptation that enable the halophytes to survive in their habitats. (2marks)
5.  
   1. What is parthenogenesis. (1mark)
   2. Monocotyledonous plants do not undergo secondary growth. Explain, (1mark)
6. Name two classes of Phylum Arthropoda whose members’ head is fused with the thorax. (2marks)
7. Name two excretory products produced by both plants and animals. (2marks)
8. The shirt of a student was stained by a solution of DCPIP. A friend advised him to wash with lemon juice. Explain. (1mark)
9. Two freshly cut banana peels A and B measuring 4cm long were cut, which were later placed in solutions of different concentrations in two separate beakers for 30minutes. The appearance after 30minutes is as shown below.
   
   
   1. What is the nature of the solution in which piece B was placed. (1mark)
   2. Account for the appearance of piece A. (3marks)
10.  
    1. The ovum is fertilized only by one sperm yet there is millions of sperm surrounding the ovum. Explain. (1mark)
    2. Give the role of the following parts of the male reproductive system.
       1. Epididymis (1mark)
       2. Prostate gland (1mark)
11.  When a person has oxygen debt the heart beat increases. Give two importance of the increase in heart beat. (2marks)
12. The diagram below shows part of a nephron from the human kidney.
    
    
    1. Give two factors that lead to creation of higher pressure in the structure labelled Q. (2marks)
    2. On the diagram above label the part where the sodium ions are reabsorbed and write down the hormone involve in regulating the level of this ions (2marks)
       Name of the hormone; ………………………………………………………………………………
13. Explain how the following parts of a light microscope are modified to perform their function
    1. Diaphragm (1mark)
    2. Mirror. (1mark)
14.  
    1. Explain two adaptations of cell membrane to its function. (2marks)
    2. Why is oxyhaemoglobin formation is highly preferred during transportation of oxygen in the body. (2marks)
15.  
    1. Explain how smoking of tobacco lead to lung cancer. (1mark)
    2. How does age affect the breathing rate in human? (2marks)
16. In an experiment to investigate an aspect of digestion, two test tubes A and B were set as shown below. The set up was left for 30 minutes and the temperature of water was maintained at 37°C.
    
    The resulting content in each test tube A and B were placed into two separate visking tubing which were then placed in a beaker containing iodine solution, for 20 minutes.
    1. What was the observation that was made in the visking tubing containing contents of test tube A. (1mark)
    2. Account for the result in visking tubing which was containing contents of test tube B. (3marks)
17. During a biological excursion a group of form 4 students collected plant specimen whose reproductive organ is shown below.
    
    
    1. Name the sub-division of the plant in which the above specimen was obtained. (1mark)
    2. Other than the presence of the above characteristics, state two characteristics of plants in the sub-division named above. (2marks)
18. Enzymes are important in various physiological processes in living things.
    1. Differentiate between an enzyme and a hormone (1mark)
    2. Name one property of an enzyme exhibited by the lock and key hypothesis (1mark)
19.  
    1. The transverse section of a young dicotyledous root was cut and iodine solution was applied. One of the part of the section turned to blue-black colour. Identify the part of the root and give a reason for your answer.
       Part ………………………………………………………………………………………… (1mark)
       Reason (1mark)
    2. Distinguish between transpiration and guttation. (1mark)
20. The diagram below shows a cell undergoing a stage in cell division.
    
    With a reason, identify this stage (2mark)
    Identify
    Reason
21.  
    1. Define the term immunity. (1mark)
    2. Identify one immunizable disease in Kenya (1mark)
    3. State two ways in which lymphocytes kill disease causing microorganism. (2marks)
22. Study the diagram below and answer the questions that follow.
    
    
    1. With an arrow, indicate on the diagram the direction of the impulse through the neuron. (1mark)
    2. State the function of the parts labelled P (1mark)
23. Name the type of response exhibited by;
    1. Sperm cell when it swims towards the ovum. (1mark)
    2. Leaves of Mimosa pudica when they fold their leaves after being touched. (1mark)
24.  
    1. Distinguish between hypogeal and epigeal germination. (1mark)
    2. State two internal factors necessary for germination (2marks)
25.  
    1. Give two importance of divergent evolution to animals (2marks)
    2. Explain two limitations of fossil record as an evidence for evolution (2marks)
26. What causes the following diseases?
    1. Diabetes mellitus (1mark)
    2. Diabetes inspidus (1mark)
27. Study the diagram below and answer the questions that follows.
    
    
    1. Identify the tooth. (1mark)
    2. Give a reason for your answer in 27(a) above (1mark)
    3. State two mineral ions deposited on the bones to harden them. (2marks)
28.  
    1. The following is food chain that was presented by a student in class.
       
       State two errors that are made in the food chain (2marks)
    2. Give a reason why pyramid of biomass is considered to be more accurate over the pyramid of numbers. (1mark)
29. Below are cross section of diagrams of fruits.
    Identify the type of placentation present in the three diagrams (3marks)
    
    P ……………………………………………………………….
    Q ……………………………………………………………….
    R ……………………………………………………………….

MARKING SCHEME

1. State the name given to the study of: (2marks)
   1. Chemical changes in living organisms
      • Biochemistry ;
   2. Insects
      • Entomology ;
2. State the category of variation into which the following traits fall. (2marks)
   1.  
      1. Skin pigmentation
         • Continuous ;
      2. Blood group
         • Discontinuous
   2. Give two possible genotype of blood group A (2marks)
      • AA, AO;
3. Give two differences between scientific names and common names. (2marks)
   

   Scientific Names	Common Names
   Universally known	Known only in local areas ;
   Written in Latin language	Written in local languages ;

4.  Explain two adaptation that enable the halophytes to survive in their habitats. (2marks)
   • Root cell with high salt concentration to offset the osmotic imbalance;
   • Some have glands that secrete excess salt ;
   • Possess succulent tissues for water storage ;
   • Mangrove has pneumatophores emerging above water to obtain air;
     Any first 2 correct
5.  
   1. What is parthenogenesis (1mark)
      • Asexual reproduction in which the unfertilized egg is produced and hatch into adult insect,,
   2. Monocotyledonous plants do not undergo secondary growth. Explain (1mark)
      • Lack cambium ;
6. Name two classes of Phylum Arthropoda whose members’ head is fused with the thorax (2marks)
   • Class Crustacea;
   • Class Arachnida ;
7. Name two excretory products produced by both plants and animals (2marks)
   • Carbon (IV) oxide;
   • Water ;
8. The shirt of a student was stained by a solution of DCPIP. A friend advised him to wash with lemon juice. Explain. (1mark)
   Lemon juice contains ascorbic acid/vitamin C which decolourizes DCPIC;
9. Two freshly cut banana peels A and B measuring 4cm long were cut, which were later placed in solutions of different concentrations in a beaker for 30minutes. The appearance after 30minutes is as shown below.
   1. What is the nature of the solution in which piece B was placed (1mark)
      • Hypotonic solution ;
   2.  Account for the appearance of piece A (3marks)
      • The banana peel was placed in a hypertonic solution, the mesocarp cells loose water by osmosis; becoming flaccid, reducing in size thus the curvature; the outer side is covered by the waterproof cuticle hence do not loose water by osmosis;
10.  
    1. The ovum is fertilized only by one sperm yet there is millions of sperm surrounding the ovum. Explain (1mark)
       • After fertilization the vitelline membrane changes its structure preventing any other sperm from entering the ovum;
    2. Give the role of the following parts of the male reproductive system
       1. Epididymis (1mark)
          • Storage of sperms ;
       2. Prostate gland (1mark)
          • Produce alkaline fluid that neutralizes vaginal fluid/ activates sperms;
11. When a person has oxygen debt the heart beat increases. Give two importance of the increase in heartbeat (2marks)
    •  Enhances faster supply of oxygen needed to breakdown the lactic acid;
    •  Transport lactic acid to the liver(converted to glycogen);
12. The diagram below shows part of a nephron from the human kidney.
    1. Give two factors that lead to creation of higher pressure in the structure labelled Q(2marks)
       • The efferent has a narrower lumen than the afferent ;
       • Renal artery branches directly from the aorta whose flows at higher pressure ;
    2. On the diagram above label the part where the sodium ions are reabsorbed and write down the hormone involve in regulating the level of this ions (2marks)
       
       Name of the hormone; Hormone Aldosterone;
13. Explain the following parts of a light microscope are modified to perform their function
    1. Diaphragm (1mark)
       • Has adjustable aperture thus able to regulate amount of light passing through the condenser;
    2. Mirror (1mark)
       • Shinny surface for reflecting light through the condenser onto the stage / Adjustable to change in position for efficient reflection of the light from the surrounding ;
14.  
    1. Explain two adaptations of cell membrane to its function (2marks)
       • Tiny spores for selective movement of materials in and out of the cell;
       • Has two phospholipid layers embedded to protein molecule, which strengthens it to enclose the cell contents;
    2. Why is oxyhaemoglobin formation is highly preferred during transportation of oxygen in the body. (2marks)
       • Oxyhaemoglobin is unstable compound which readily dissociates to release oxygen; creating room for transportation of more oxygen ;
15.  
    1. Explain how smoking of tobacco lead to lung cancer (1mark)
       • Burning tobacco has tar which triggers lung cells to become cancerous;
    2. How does age affect the breathing rate in human? (2marks)
       • Younger people have higher breathing rate than aged people; since they are actively growing thus require more oxygen for respiration which provide energy for cell division;
16. In an experiment to investigate an aspect of digestion, two test tubes A and B were set as shown below. The set up was left for 30 minutes and the temperature of water was maintained at 370C.
    The resulting content in each test tube A and B were placed into two separate visking tubing which were then placed in a beaker containing iodine solution.
    1. What was the observation that was made in the visking tubing containing contents of test tube A. (1mark)
       • Content in the visking tubing turned to brown colour;
    2. Account for the result in visking tubing which was containing contents of visking tubing B (3marks)
       • Content in the visking tubing B turned to blue black colour; iodine has small molecules thus diffused through the visking tubing reacting with starch forming the blue black substance; starch has larger molecule hence unable to pass through the tiny pores of the visking tubing ;
17. During a biological excursion a group of form 4 students collected plant specimen whose reproductive organ is shown below.
    1. Name the sub-division of the plant which the above specimen was obtained. (1mark)
       • Gymnospermaphyta;
    2. Other than the presence of the above characteristics, state two characteristics of plants in the sub-division named above. (2marks)
       • Presence of needle like leaves/ show xerophytic characteristics / Non-flowering /Xylem made up of mainly tracheids / Phloem lack companion cells; Any first 2 correct
18. Enzymes are important in various physiological processes in living things.
    1. Differentiate between an enzyme and a hormone (1mark)
       • Enzymes are organic catalysts which regulate biochemical reactions in the body cell, while hormone are organic compounds which influence biological activities;
    2. Name one property of an enzyme exhibited by the lock and key hypothesis (1mark)
       • Substrate specific;
19.  
    1. The transverse section of a young dicotyledous root was cut and iodine solution was applied. One of the part of the section turned to blue-black colour. Identify the part of the root and give a reason for your answer.
       Part (1mark)
       • Endodermis;
         Reason (1mark)
       • Has starch grains which stain blue-black with iodine solution;
    2. Distinguish between transpiration and guttation (1mark)
       • Transpiration is the process by which plant lose water inform of water vapour through the stomata, while guttation plant lose water in form of droplets through hydathodes;
20. The diagram below shows a cell undergoing a stage in cell division.
    • With a reason, identify this stage (2mark)
    • Identify Metaphase I rej. Metaphase alone ;
    • Reason Bivalent chromosomes lie up together at the equator ;
21.  
    1. Define the term immunity. (1mark)
       • Ability of the body to develop resistance against disease causing microorganisms in the body ;
    2. Identify one immunizable disease in Kenya (1mark)
       • Measles /Polio/Tetanus /Whooping cough /Pneumonia;
    3. State two ways in which lymphocytes kill disease causing microorganism. (2marks)
       • Antitoxins neutralized the toxins /Agglutinins causes crumping together of the disease causing microorganisms /Lysins digest the cell membrane of the microorganisms /Opsonin adhere on the outer surface of the microorganisms; Any first two correct
22. Study the diagram below and answer the questions that follow.
    1. With an arrow, indicate on the diagram the direction of the impulse through the neuron (1mark)
       
       
    2. State the function of the parts labelled P (1mark)
       Insulate the axon/enhances the rapid transmission of nerve impulse;
23. Name the type of response exhibited by;
    1. Sperm cell when it swims towards the ovum (1mark)
       • Positive chemotaxis ;
    2. Leaves of Mimosa pudica when they fold their leaves after being touched. (1mark)
       • Haptonastism;
24.  
    1. Distinguish between hypogeal and epigeal germination (1mark)
       • Hypogeal germination cotyledons remains below the ground surface (when epicotyle elongates push out the soil) while epigeal germination cotyledons are brought above the ground surface (when hypocotyl elongates then straightens);
    2. State two internal factors necessary for germination (2marks)
       • Enzymes ;
       • Hormones ;
       • Viability ; Any first two correct
25.  
    1. Give two importance of divergent evolution to animals (2marks)
       • Results to adaptation that enables organisms to exploit different ecological niches ;
       • Leads to formation of new species; Acc. Speciation
    2. Explain two limitations of fossil record as an evidence for evolution (2marks)
       • Some fossil records are missing ;
       • Destruction of fossils by geological activities ;
       • Wrong impression of the structures due to distortion during sedimentation; Any first two correct
26. What causes the following diseases?
    1. Diabetes mellitus (1mark)
       • Inability of pancreas to secret insulin/ Produce inadequate amount;
    2. Diabetes inspidus (1mark)
       • Inability of pituitary gland to secrete antidiuretic hormone/ Produce inadequate amount;
27. Study the diagram below and answer the questions that follows.
    1. Identify the tooth (1mark)
       • Premolar/molar;
    2. Give a reason for your answer in (a) above (1mark)
       • Two root/cusps/ridges/broad surface ;
    3. State two mineral ions deposited on the bones to harden them. (2marks)
       • Calcium ions ;
       • Phosphate ions ;
28.  
    1. The following is food chain that was presented by a student in class.
       • Grasshopper Lizard Chicken Hawk
         State two errors that are made in the food chain (2marks)
       • No producer ;
       • Lizard to chicken energy flow is reversed ;
    2. Give a reason why pyramid of biomass is considered to be more accurate over the pyramid of numbers (1mark)
       • Pyramid of biomass takes into account the body size of the organism in each trophic level; whereas pyramid of numbers only consider the number of organisms in each trophic level and not their body size;
29. Below are cross section of diagrams of fruits.
    Identify the type of placentation present in the three diagrams (3marks)
    P Axile ;
    Q Parietal ;
    R Free central ;