Biology Paper 2 Questions and Answers - Mathioya Mock 2021 Exams

INSTRUCTIONS TO CANDIDATES

• This paper consists of two sections Section A and section B
• Answer ALL questions in section A in the spaces provided In section B answer question 6 (compulsory) and either question 7 or 8 in the spaces provided after question 8

For Examiners use only

QUESTIONS

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

1. A form one student carried out an experiment using a potato cylinder as shown below
   
   
   1. Name the physiological process being investigated (1mk)
   2. Give the name given to solution X and Y in relation to the potato cell sap
      1. Solution X (1mk)
      2. Solution Y (1mk)
   3. Give three roles of the process demonstrated above in plant (3mks)
   4. Give the property of cell membrane that enables it to carry the following functions
      1. A nerve cell to conduct nerve impulse along the nerve fibre (1mk)
      2. Control movement of substances in and out of the cell (1mk)
2.                      
   1. Give two features of gill filaments that adapt them to their function (2mks)
   2.                  
      1. Give two ways in which corona virus is transmitted (2mks)
      2. State how the following precautions prevent spread of corona virus
         1. Wearing a face mask (1mk)
         2. Washing hands with soap and water (1mk)
   3.                    
      1. Name the part of the brain that control breathing (1mk)
      2. Name the bacteria that causes tuberculosis (1mk)
3.                
   1. A farmer planted his bean seeds after the onset of rain, seven days later, none had germinated Give possible reasons for this observation (3mks)
   2. Give two roles of water in seed germination (2mks)
   3. A student observed that when a shoot is cut one feet from the top, it no longer increase in height Explain possible reasons (3mks)
4. Birds and insects have wings for flying but they have different internal structures
   1.                                
      1. Give the name given to such structures (1mk)
      2. Give the type of evolution that leads to development of such structures (1mk)
   2. Explain the term natural selection as used in biology (2mks)
   3.                  
      1. A malaria drug called malariaquine is no longer effective for treatment of malaria after being used for a long time Explain possible reasons (2mks)
      2. Give two evolutionary characteristics that adapt man to his environment (2mks)
5. The diagram below represent a mammalian skull
   
   
   1.                      
      1. Giving reasons, name the mode of nutrition for the animal
         Mode of nutrition (1mk)
         Reasons (2mk)
      2. Name part labelled N (1mk)
   2. The diagram shows digestive system in man
      
      
      1. Name an enzyme produced by organ labeled M that assist in digestion of a piece of
         1. Cassava (1mk)
         2. Lean meat (1mk)
   3.                  
      1. Give the function of the juice produced by organ labeled K (2mks)

SECTION B (40 marks) Answer Question 6 (Compulsory) and Either question 7 or 8

6. A group of students investigated the relationship between the rainfall pattern and the number of plant species eaten by certain herbivorous mammal throughout the year The results were as shown in the table below
   

   Month	Jan	Feb	Mar	April	May	June	July	Aug	Sep	Oct	Nov	Dec
   Amount of Rainfall (mm)	12	20	50	120	180	180	160	100	40	60	80	20
   No of plant species eaten	120	100	68	50	30	20	30	40	68	60	50	100

   1. On the same axis draw a graph of amount of rainfall and number of plant species eaten against months of the year (8mks)
      
   2. Giving reasons ,name the month when the mammal was most selective in its feeding (3mks)
   3. Account for the change in the number of plant species eaten during the month of December, January and February(3mks)
   4. What is the advantage of the type of feeding behavior exhibited by the mammal? (1mk)
   5. Suggest two methods that may have been used to determine the plant species eaten by this mammal (2mks)
   6. Apart from light ,name three environmental factors that would affect carbon (iv)oxide concentration in a given forest (3mks)
7. Discuss the practical application of knowledge of genetics (20 mks)
8. Explain how the following types of plants are adapted to their habitat
   1. Xerophytes (13 mks)
   2. Hydrophytes (7 mks)

MARKING SCHEME

1.                    
   1. Osmosis; (1mk)
   2.                                  
      1. Isotonic solution; (1mk)
      2. Hypotonic solution; (1mk)
   3. Feeding in insectivorous plants;
      • Absorption of water from the soil;
      • Support;
      • Opening and closing of stomata;
        (3mks) mark 1st three
   4.                    
      1. Possession of electric charges /polarity; 1mk
      2. Semi-permiability;1mk
2.                  
   1. Moist surfaces;Rj moist alone
      Numerous to increase surface area for gaseous exchange.
      Highly vascularised;OWTTE.
      Large surface area /enlongated;
      Thin membrane /one cell thick; 2mks (mark 1st two)
   2.                    
      1. From contaminated surfaces then transferred to mouth /nose/eyes;(through hands)
         -Inhaling air contaminated with droplets and small particles containing the virus; 1 mk
      2.                      
         1. Filter out particles containing the virus from inhaled /exhaled air reducing infection; 1mk OWTEE
            -Limit the volume and travel distance of expiratory droplets when talking or breathing ; OWTTE 1mk
         2. Kill the virus /soap dissolve virus lipid coat hence killing it ;1 mk
         3.                      
            1. Medulla oblongata; (1mk
            2. Mycobacterium tuberculosis; 1mk
3.                  
   1. Presence of abscisic acid /germination inhibators;
      Embryo not fully developed;
      Impermeamble seed coat;
      -Embryo destroyed by pest;
      Absence of growth promoters/
      Enzymes that control germination;
      Mark 1st three 3mks
   2. Hydrolysis of stored food;
      Transport medium ;
      Soften seed coat;
      Unfavourable temperature 2mks mark 1st two
   3. The tip of the shoot containing auxin was removed ;apical growth takes place only at the tip under influence of auxin; Hence apical dorminance removed 3mks
4.                            
   1.                        
      1. Anlogous structure; 1mk
      2. convergent evolution; 1mk
   2. This is the process where nature selects organisms with favourable characteristics /traits well adapted to prevailing environmental conditions survive; reach adulthood and reproduce giving forth offsprings that inherit the favourable characteristics ;while those with unfavourable characteristics do not survive the competition die young and their genes are eliminated from nature; 3 mks
   3.                    
      1. The malaria parasite (plasmodium) mutated and become resistant to the drug. This characteristics are transmitted to the offspring ;(survive in presence of the drug) 2mks
      2. Erect posture/upright /bipedal gait;
         -Enlarged brain capacity /higher intellectual capacity.
         -Communication through speech /language
         -Prehensible fore limb
         -Binocular vision;
         Mark 1sttwo 2mks
5.                          
   1.                          
      1. Mode -:Herbivory Rj herbivore
         Reasons-:Lack of upper incisors/presence of a horny pad
         -Presence of diastema;1mk
      2. horny pad;1mk
   2.                      
      1. (paucreatic )Amylase;
      2. trypsin;1mk
6.                        
   1. Scale 2mks
      Axis 2mks
      Plotting 2mks
      Curve 1mk
      Labeling 1mk
      
      8mks
   2. June ;rainfall highest so productivity per plant species highest / abundant food; so mammals eats its most favourable plant species only;3mks
   3. The number of plant species eaten is highest /high ;There is less rain during the months so less amount of food available /less productivity per plant species ;forcing the animals to eat a number of different species to meet its food requirement; (3mks)
      The animal is able to obtain its dairy fopod requirements irrespective of seasonal charges; 1mk
   4. Observe and record plant species eaten /Analyse the animals dropping ;Fistulation; 2mks
7. applicationof geneticknowledge today.
   1. In blood transfusion.;
      Blood typing  AB antigen and rhesus antigen is necessary to ensure compatibility of recipient's and donor's blood to prevent agglutination.;
   2. Genetic counselling.:
      Where couples are advised on chances of offspring's inheriting hereditary disease~e.g. Sicklecell anemia, hemophilia, albinism etc.;
      Also some hereditary disorders are scientifically explainecd e.g.hemolytic diseaseofthe newborn, turners' syndrome andDownsyndrome. J
   3. In solving disputed parentage.;
      The knowledge of blood groups inheritance and DNA matching are being used as supportive evidencein courts where parentage isdisputed.:,-
   4. Inplantsandanimal breeding._;
      Bettercropsandlivestockareselectedthencrossedrespectively toproduce individuals with better . performance/ higherheterozygozity/ higherhybrid.;
   5. Inmediciner
      Inmedicine anorganismcalledEscherichiacoliE.coli hasbeenmodified toproduce a hormone called somatotrophin forthetreatment ofdwarflsrn.z
      Thefungus(yeast)hasbeenmodified toproduceanti-hepatitis-B vaccine.;
      Insheepthere hasbeenmodification toproducemilkwith medicinal proteins torelief h~mophilia and emphysema.; "
      Ingenetherapy wherefaulty genesarereplacedwith normalonestocorrect genetic disorders'e.g. Lung cysticfibrosis. ; '
   6. lntheenvironment.;
      Agenetically modified pseudomonous bacterium capableofbreakingdown synthetic hydrocarbon has beendeveloped tocontrol pollution.;
   7. Incrimedetection.z
      DNA/finger printing fromthesceneofcrimeandsuspectshairsorbloodsamplesorsemenfrom thesuspectshasbeenusedtoidentify criminals.;
   8. Incloning.;
      Ithasbeenusedtoasexually(without fertilization) producing genetically identical offsprings e.gdolly thesheep.;Clonescan beusedtoproduce humanspareparts.;
   9. Inagriculture;
      Intissueculture newvarieties ofpyrethrum, bananahasbeenproduced.
   10. Ingenetic engineering.;
       Desirable genes are identified,altered,isolated and transferred; (to another organism)
8.                    
   1.  Xerophytes
      • Roots extensively developed /superficial roots ;to provide large surface area;
      • Roots grow deep/long roots;to reach water source deep in the ground;
      • Sacculent /fleshy/possession of water storage tissues ;to store water /to survive drought;
      • possession of thick waxy cuticle;
      • hairly leaves;sunken stomata;
      • Reduced leaf size /spines /scales/thorns/reduced number of stomata/needle shaped leaves;
      • Rolled leaves Acc folded leaves; shedding of leaves;
      • rolled leaves Acc folded leaves;s hedding of leaves;
      • Reversed stomatal rhythm; to reduce rate of transpiration;
      • short life cycle /quick growth after rain; to make use of available water quickly; 16mks max 13
   2. Hydrophytes
      • Aerenchyma/air spaces /large intercellular spaces/long fibrous roots ;for bouyency/floating in water;
      • Poorly developed conducting tissue /xylem and phloem;plants obtain water by diffusion ;
      • Poorly developed supportive tissue (schlerenchyma;because water provide necessary support;
      • Upper epidermis of leaves have more stomata than the lower epidermis;for gaseous exchange /for increased rate of transpiration;
      • ACCb all stomata on the upper side 8mks.