K.C.S.E Biology Q & A - MODEL 2017PP2QN02
The table below shows variations in the form carbon (IV) oxide is transported in the blood at rest and during physical exercise.
​(a) Explain why more carbon (IV) oxide ¡s transported in the form of bicarbonate ion.
(b)Account for the high total plasma content of carbon (IV) oxide during exercises. (c) State how one’s involvement in the exercises affects blood pH. (d) Name the protein responsible for the transport of carbon (IV) oxide in the blood.
ANSWERS
​(a) Presence of carbonic anhydrase enzyme; which speeds up the conversion of carbon (IV) oxide to weak carbonic acid; which dissociates into hydrogen carbonate ion/(HCO3) (that diffuses out of the red blood cells into the blood plasma);
(b)The body needs high amount of energy; (for the exercise/muscle activity) hence high respiration rate (more oxygen intake); releasing more carbon (IV) oxide (in the blood plasma); (c)The high rate of respiration (during physical exercises coupled with normal cellular metabolism) results in the production of more carbon(IV) oxide/faster accumulation of lactic acid; lowering the blood plasma pH/making it more acidic (compared to when one is at rest); (d)Haemoglobin  K.C.S.E Biology Q & A - MODEL 2017PP2QN01
The diagram below represents a nucleus.
​(a) Name the structures labelled E and F.
(i) E F (ii) State the function of F. (iii) With reference to the nucleus, state one difference between an animal and a bacterial cell. (b) Name the plant cell organelle: (i) that stores chlorophyll (ii) responsible for intracellular digestion. (c) State two main functions of the vacuole in the amoeba.
ANSWERS
​(a) E—Nucleolus;
F — Nuclear pore/nucleopore; ii. Facilitates movement of materials in and out of the nucleus; iii. Nuclear material in the bacterial cell is not enclosed within a membrane /prokaryotic, while in animal cell it is enclosed eukaryotic; (b) i. Chloroplast; ii. Lysosome; (c) i. Feeding (food vacuole); ii. Osmoregulation (contractile vacuole); iii. Excretion/removal of wastes; K.C.S.E Biology Q & A - MODEL 2017PP1QN23
The diagram below represents a set up during an experiment.
​(a) (i) What was, the experiment investigating?
(ii) State the likely identity for substance K (iii) Explain your answer in (a) (ii) above (b) Account for the observations made in flask 2.
answers
​a.) i) To investigate how ants respond to moisture/water hydrotaxis (varied environments with/without moisture water);
ii) Silica gel/anhydrous calcium chloride pellets/pyrogallic acid/dehydrating drying agent; iii) The colour of cobalt (II) chloride paper remained blue/all the moisture water vapour was absorbed/There was no water/moisture in the flask to change the colour of cobalt(II) chloride paper; b.) (More) ants were attracted) moved into the flask; due to the presence of moisture/water vapour; (evidenced by the change of cobalt (II) chloride paper to pink)
K.C.S.E Biology Q & A - MODEL 2017PP1QN22
State two ways by which plants manage their solid wastes.
answers
K.C.S.E Biology Q & A - MODEL 2017PP1QN21
The photograph below represents a leaf obtained from a certain plant.
​Account for the observations made if the leaf was tested for starch.
answers
K.C.S.E Biology Q & A - MODEL 2017PP1QN20
State three methods of fossil formation.
answers
​i. Petrification/change into rock;
ii. Entire organism or parts preserved; iii. Impressions (e.g. casts/moulds); K.C.S.E Biology Q & A - MODEL 2017PP1QN19
The table below shows the percentage concentration of certain substances in blood plasma, glomerular filtrate and urine in a human being at a particular time.
​(a) Explain the likely impact on the composition of urine in case of the following:
(i) Vigorous physical exercises (ii) a meal rich in proteins (b) Name the processes responsible for: (i) Presence of glucose in the glomerular filtrate (ii) absence of glucose in urine
answers
​a. i) Less water and urea; since sorne is excreted/eliminated through the skin (as sweat);
ii) increased amount of urea in the urine; due to deamination of amino acids (from proteins); b. i) ultra filtration; ii) Selective reabsorption; K.C.S.E Biology Q & A - MODEL 2017PP1QN18
Below are diagrams representing developmental stages of three different vertebrates.
​(a) State the evidence of evolution illustrated by the vertebrates in the diagram.
(b) Suggest why the structure labelled J has been retained throughout the evolution of fish. (c) State two major advantages evolution has given humans Over most of the other animals.
answers
K.C.S.E Biology Q & A - MODEL 2017PP1QN17
How is the surface area increased in the mammalian small intestines?
answers
K.C.S.E Biology Q & A - MODEL 2017PP1QN16
The following are text messages on a celiphone that represent gene mutation.
​(a) Identify the type of gene mutation represented in each case
I II (b) State Mendel’s First Law. (c) State two disadvantages of genetically modified plant products.
answers
​a. I — Deletion;
II- Inversion; b. The characteristics /traits of an organism are determined by internal factors/ genes (which occur in pairs). Only one of the genes can be carried in a gamete/ passed onto the next generation; c. Most have lost most of the original (desirable) qualities e.g taste; Poor/undesirable qualities are perpetuated through subsequent generations; Products’ qualities are irreversible- can’t get original species/qualities;
K.C.S.E Biology Q & A - MODEL 2017PP1QN15
Explain the physiological process responsible for keeping young seedlings upright.
answers
K.C.S.E Biology Q & A - MODEL 2017PP1QN14
The photograph below illustrates a germinating seedling.
​(a) Name the type of germination illustrated in the photograph.
(b) Explain the function of each of the parts labelled G and H. G H
answers
​ a. Epigeal;
b. G- Elongates to expose the foliage leaves to light photosynthesis H- Stores food (for growth); For photosynthesis (it is green); Protects plumule during germination;
K.C.S.E Biology Q & A - MODEL 2017PP1QN13
Name the causative agent for Tuberculosis
answers
K.C.S.E Biology Q & A - MODEL 2017PP1QN12
Explain the survival values of the following tropic responses to plants.
(a) Geotropism (b) Phototropism
answers
K.C.S.E Biology Q & A - MODEL 2017PP1QN11
The set up below illustrates a certain physiological process.
​(a) (i) Name the physiological process.
(ii) Give two examples of the process named in (a) (i) above in plants. (b) State two ways by which the movement of dye molecules in the set up would be slowed down.
answers
​a i) Diffusion;
ii) Gaseous exchange/excretion of carbon (IV) oxide and oxygen; Translocation of materials; Absorption/uptake of mineral ions/salts; b. Lowering the temperature of the medium; Increasing thickness of the membrane; Use less dye/add more water/reducing the concentration gradient;
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