Below is a photograph of Brassica oleracea, Sukuma wiki leaf.

​(a)State two observable features that adapt the leaf to gaseous exchange.
(b) Explain the relationship between photosynthesis and aerobic respiration within the leaf.

In an investigation, two potted plants G and H belonging to the same species were exposed to increasing light intensities at different temperatures, 30°C and 20°C respectively. The rate of photosynthesis was measured for each plant and results recorded as shown in the table below:

​(a) On the same axis, plot graphs of rate of photosynthesis against light intensity for plants G and H. 
(b) State the aim of the investigation. 
(c) Account for the difference in the rate of photosynthesis in the two plants.
(d) Account for the difference in the rate of photosynthesis in the two plants between the following light intensities:
(i) 1—4 units 
(ii) 4—8 units. 
(e) (i) Predict the rate of photosynthesis at light intensity of 16 units. 
(ii) Give a reason for your answer in (e) (i) above. 
(f) State one internal and one external factor that could be limiting in the investigation.

In an experiment to investigate a factor affecting photosynthesis, a potted plant which had been kept in the dark overnight was treated as shown in the diagram below and exposed to light.

​(a) Why was the potted plant kept in the dark overnight’? 
(b) Which factor was being investigated in the experiment? 
(c) (i) Which test did the students perform to confirm photosynthesis in the leaves labelled P and Q? 
(ii) State the results obtained in the leaves labelled P and Q.
P             
Q              
(iii) Explain the results obtained in the leaves labelled P and Q. 
P
Q           
(d) What was the purpose of leaf Q in the experiment?

K.C.S.E Biology Q & A - MODEL 2015PP1QN17

Explain how each of the following factors affects the rate of photosynthesis:
(i) temperature; 
(ii) chlorophyll concentration.

(a) Explain the importance of the following in photosynthesis: 
(i) light;
(ii) carbon(IV) oxide;
(iii) chlorophyll.

(b) Name one appropriate food substance for each of the following enzymes: 
(i) ptyalin 
(ii) pepsin
(c) State the cause and two symptoms of Ben-ben.
 Cause             
Symptoms ​

Explain how the following factors affect the rate of photosynthesis:
(a) Concentration of carbon (iv) oxide 
(b) Light intensity 

The equation below represents a process that takes place in plants
 6CO2 + 6H2O→C6H12O6 + 602
(a) Name the process 
(b) State two conditions necessary for the process to take place 
(c) State what happens to the end- products of the process 

Name the sites where light and dark reactions of photosynthesis take place 
Light reaction
Dark reaction

The diagram below represents a set up that was used to investigate certain process in a plant

(a) State the process that was being investigated 
(b) State a factor that would affect the process 

K.C.S.E Biology Q & A - MODEL 2007PP1QN06

K.C.S.E Biology Q & A - MODEL 2006PP1QN27

K.C.S.E Biology Q & A - MODEL 2004PP1QN09

K.C.S.E Biology Q & A - MODEL 2003PP1QN10

In an experiment to investigate a factor affecting photosynthesis, a leaf of a potted  plant which had been kept in the dark overnight was covered with aluminum foil as shown in the diagram below

The set up was kept in sunlight for three hours after which a food test was carried out on the leaf.
(a) Which factor was being investigated in the experiment?
(b) What food test was carried out?
(c) (i) State the results of the food test
(ii) Account for the results in c (i) above
(d) Why was it necessary to keep the plant in darkness; before the experiment?