INSTRUCTIONS TO CANDIDATES
Answer ALL the questions in the spaces provided.
- You are provided with
Spécimen X
Solution Y
Solution Z- Examine the outer and inner leaves then record your observations (4mks)
- Using a scalpel, cut and measure 6strips of 3cm length of the specimen X. Place 3 strips into a solution labeled Y, another 3 strips into a solution labeled Z. The experimental set up is allowed to stand for 20 minutes.
- What observations would be made after 20 minutes when the strips are touched (2mks)
Strips in solution Y
Strips in solution Z - Account for the observations recorded in (b) (i) above (4mks)
- What observations would be made after 20 minutes when the strips are touched (2mks)
- You are provided with actual specimens of plant parts Q and K
-
- Using external features only identify the part of the plants (2mks)
- Give three reasons for your answer in (a) (i) above (3mks)
- With reasons state the class to which the plants from which the specimens were obtained belong (4mks)
- State two observable features that adapt specimen Q for gaseous exchange (2mks)
- Using the dichotomous key provided, indentify the identity of the specimens Q and K in each case show the sequence; the steps in the key that you followed to arrive at the identity. (4mks)
-
-
- Leaf parallel veined……………………………………………..go to 2
- Leaf net veined …………………………………………………go to 4
-
- Leaf purple in colour…………………………..………Tradescantia spp
- Leaf green in colour …………………………… ……………….go to 3
-
- Leaf with thorns on margin………………… ……………Kalanchoe spp
- Leaf smooth on the margin……………… ……………………Zea mays
-
- Leaf sample………………………… …………………………….go to 5
- Leaf compound……………………………………………………go to 8
-
- Leaf margin entire …………………………………………………go to 6
- Leaf margin serrated……………………………………………..Habiscus
-
- Leaf texture rough………………………………………………….go to 7
- Leaf texture smooth……………………….…………………..Brassica spp
-
- Leaf blade Lanceolate…………………….…………………..Solanum spp
- Leaf blade broad……………………………………………Lantana camara
- The photography below shows four specimens labeled P, Q, R and S, which were obtained from the same animal. Examine them
- With reasons identify P and Q (4mks)
P-
Reason-
Q-
Reason- - Based on their structure, suggest the functions of specimens P and Q (2mks)
P-
Q- - In specimen P, name the four parts labeled A to D (4mks)
A B C D - Using observable features, state the differences between R and S (3mks)
- Explain how specimen S is adapted for its functions (2mks)
- With reasons identify P and Q (4mks)
CONFIDENTIAL
- X - Onion bulb ( Each student 1⁄4 )
Y – Distilled water
Z – concentrated sodium chloride
- scalpel
- labels
Petri- dishes / beakers
- Q – sukuma wiki
K – maize leaf
MARKING SCHEME
- You are provided with
Spécimen X
Solution Y
Solution Z- Examine the outer and inner leaves then record your observations (4mks)
Outer leaf – papery / dry / scaly / dehydrated
- Thin / membranous
- Pigment
Inner leaf – succulent - Thick
- swollen
- Using a scalpel, cut and measure 6strips of 3cm length of the specimen X. Place 3 strips into a solution labeled Y, another 3 strips into a solution labeled Z. The experimental set up is allowed to stand for 20 minutes.
- What observations would be made after 20 minutes when the strips are touched (2mks)
Strips in solution Y- feel firm / turgid / hard
Strips in solution Z – feel soft / flabby / flaccid / tender - Account for the observations recorded in (b) (i) above (4mks)
The concentrated solution Z is hypertonic to the cell sap therefore the cell lose water by osmosis cells become flaccid / flabby.
The distilled water (Y) is hypotonic to the cells gain water by osmosis and the strips because hard / turgid
- What observations would be made after 20 minutes when the strips are touched (2mks)
- Examine the outer and inner leaves then record your observations (4mks)
- You are provided with actual specimens of plant parts Q and K
-
- Using external features only identify the part of the plants (2mks)
Leaf - Give three reasons for your answer in (a) (i) above (3mks)
- Presence of leaf
- Presence of midrib
- Presence of veins
- Using external features only identify the part of the plants (2mks)
- With reasons state the class to which the plants from which the specimens were obtained belong (4mks)
Q K Class Dicotyledonae monocotyledonae Reason broad leaf
net venationnarrow
parallel - State two observable features that adapt specimen Q for gaseous exchange (2mks)
Has a broad, flat Lamina that offers a large surface area for gaseous exchange
It is thin, thus reducing the distance over which diffusion of gases from the atmosphere to the inner most cells take place - Using the dichotomous key provided, indentify the identity of the specimens Q and K in each case show the sequence; the steps in the key that you followed to arrive at the identity. (4mks)
-
- Leaf parallel veined……………………………………………..go to 2
- Leaf net veined …………………………………………………go to 4
-
- Leaf purple in colour…………………………..………Tradescantia spp
- Leaf green in colour …………………………… ……………….go to 3
-
- Leaf with thorns on margin………………… ……………Kalanchoe spp
- Leaf smooth on the margin……………… ……………………Zea mays
-
- Leaf sample………………………… …………………………….go to 5
- Leaf compound……………………………………………………go to 8
-
- Leaf margin entire …………………………………………………go to 6
- Leaf margin serrated……………………………………………..Habiscus
-
- Leaf texture rough………………………………………………….go to 7
- Leaf texture smooth……………………….…………………..Brassica spp
-
- Leaf blade Lanceolate…………………….…………………..Solanum spp
- Leaf blade broad……………………………………………Lantana camara
K 1a, 2b, 3b, - Zea mays
Q – sukuma wiki 1b, 4a, 5a, 6b, - Brassica spp
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-
- The photography below shows four specimens labeled P, Q, R and S, which were obtained from the same animal. Examine them
- With reasons identify P and Q (4mks)
P- Molar
Reason
- Biting surface is wide and has cusps / ridges
- Presence of 3 roots
Q - Incisor
Reason-biting surface is chisel shaped / wedge shaped - Based on their structure, suggest the functions of specimens P and Q (2mks)
P - Grinding and crushing of food
Q - Gripping and cutting food - In specimen P, name the four parts labeled A to D (4mks)
A cusps
B crown
C neck
D root - Using observable features, state the differences between R and S (3mks)
R has a pointed biting surface while S has a broad biting surface with cusps / ridges
R has one root while S has 2 roots
R is smaller than S - Explain how specimen S is adapted for its functions (2mks)
It has cusps / ridges on its biting surfaces that enable crushing and grinding of food
- With reasons identify P and Q (4mks)
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