BIOLOGY
PAPER 3
INSTRUCTIONS TO CANDIDATES
- Write your name and index number in the spaces provided above.
- Sign and write the date of examination in the spaces provided above.
- You are required to spend the first 15 minutes of the 1 ¾ hours allowed for this paper reading the whole paper carefully before commencing your work.
- Answers must be written in the spaces provided in the question paper.
For Examiner’s Use only:-
Question |
Maximum Score |
Candidate’s Score |
1 |
14 |
|
2 |
13 |
|
3 |
13 |
|
TOTAL |
40 |
QUESTIONS
- Below are photographs of two specimens, J and Both of them belong to the same phylum and class. Observe them carefully before you answer the questions that follow.
- Name the class to which J and K belong and support your answer with two reasons.
Class ………………………………………………………………………………….1mk
Reasons 2mks- ……………………………………………………………………………
- ……………………………………………………………………………
- Suggest why the circulatory fluid in J and K has no haemoglobin. 2mks
- Observe their wings and suggest the type of evolution that could have taken place to give rise to J and K, and then give a reason for your answer.
Type of evolution …………………………………………………………………1mk
Reason ………………………………………………………………………………………………………………………………………………2mks - Below is a diagram showing the life cycle of specimen J.
- Identify the stage labeled D. ……………………………………………………..1mk
- Name the hormone responsible for the change from D to A. 1mk
- Explain the differences in the change from C2 to C3 and from C3 to D. 4mks
- Name the class to which J and K belong and support your answer with two reasons.
Q2. Study the organisms below and answer questions in spaces provided .
- Complete and use the key below to identify the organism. 2mks
1a. Organism with endoskeleton ………………………………………… go to 2
1b. ______________________ ………………………………………………… go to 3
2a. Has scales on the body………………………………………………… go to 4
2b. Has no scales on the body…………………………………… mammalian.
3a. Has cephalothorax ………………………………………………… Arachnida.
3b. Has no cephalothorax………………………………………………go to 5
4a. __________________________________............................... pisces
4b. Has no fins …………………………………………………….. Go to 7
5a. Has three pairs of legs …………………………………………… Insects.
5b. Has more than three pairs of legs …………………………… go to 6
6a. Two pairs of legs per segment ……………………………………Diplopoda
6b. One pair of legs per segment………………………………………chilopoda.
7a. Has feathers ……………………………………………………………… Aves
7b. Has no feathers …………………………………………………………go to 8
8a. Has a tail…………………………………………………………………Reptilia
8b. Has no tail……………………………………………………………Amphibia. - Identify the organisms above using the completed key above. 6mks
Specimen Steps followed Identity A B C D E F -
Name the phylum in which specimens C, E and F belong to ……………………………………………..1mk
-
Give three reasons for your answer in (c). 3mks
-
Name one feature that is common in organisms B, D and E. 1mk
Q3.You are provided with a specimen labeled T which is a fruit. Use it to answer the questions that follow.
- Make a transverse section of the specimen T. Draw and label at least 3 parts. 6mks
- With reasons, state the identity of fruit
Type of fruit………………………………………………………………………..1mk
Reason …………………………………………………………………………………1mk - Suggest the possible agent of dispersal and give two reasons
Agent …………………………………………………………………………………1mk
Reason ………………………………………………………………………………………………………2mk - What is the placentation of T? …………………………………………………….1mk
- Specimen T was green in colour before it was treated with a plant hormone.
Suggest the plant hormone.………………………………………………………………………………………1mk
Marking Scheme
- Below are photographs of two specimens, J and K. Both of them belong to the same phylum and class. Observe them carefully before you answer the questions that follow.
- Name the class to which J and K belong and support your answer with two reasons.
Class Insecta; 1mk Rej. insect
Reasons 2mks
i). Six legs; three body parts; two antennae; two compound eyes; - Suggest why the circulatory fluid in J and K has no haemoglobin. 2mks
Haemoglobin used to transport oxygen/ carbon (IV) oxide in the body; oxygen is taken directly to tissues/ carbon (IV) oxide taken directly from tissues by tracheoles; - divergent evolution; 1mk
Reason one pair of wings in J reduced to halters/ are vestigial; but both are functional in K 2mks -
- pupa stage; 1mk
- Ecdysone; accept Moulting hormone 1mk
- 4mks
C2 to C3 – moulting hormone / Ecdysone induce moulting; but presence of juvenile hormone prevent formation of pupa;
C3 to D – moulting hormone / Ecdysone induce moulting; but abscence of juvenile hormone lead to formation of pupa;
- Name the class to which J and K belong and support your answer with two reasons.
-
- 1b – organism with exoskeleton
4a. – has fins -
Specimen Steps followed Identity A 1a, 3a Arachnida B 1a, 2a, 4a Pisces C 1b,3b, 5b, 6b Chilopoda D 1a, 2a, 4b, 7b, 8a Reptilian E 1a, 2a, 4b, 7a, Ave F 1b, 3b, 5a Insect -
Arthropoda
rej: Anthropoda or arthropoda -
They all have exoskeleton
They have segmented bodies
They all have jointed appendages/limbs -
Scales
- 1b – organism with exoskeleton
3.
-
5mks
Magnification between X1 and X5 - Type of fruit Berry 1mk
Reason has many seeds 1mk
Agent Animal 1mk
Reason brightly coloured; scented; fleshy; large; first 2mk - Axile; 1mk
- Ethylene/ ethyne; 1mk
CONFIDENTIAL
Each candidate should have:
- One ripe banana
- Scalpel/blade
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