Question

(i) Draw a neat and well-labelled diagram of the chloroplast. 

(ii) List the events taking place in the photo-chemical phase of photo-synthesis. 

(iii) If you are planning an experiment to shew the effect of light on photosynthesis: 

(1) Will you select white light or green light ? Justify your answer. 

(2) Why would you select a destarched plant ?

Answer 1

(i)

(ii)

(ii) Following events take place in the photo-chemical phase of photo¬synthesis : 

(1) Activation of chlorophyll. 

(2) Splitting of water (Photolysis).

(3) The hydrogen ions are picked up by a compound NADP to form NADPH.

(4) The oxygen component is given out as molecular oxygen. 2O ——> O₂ 

(5) The electrons are used in converting ADP into energy rich compound ATP by adding one phosphate group P₂.

(iii) (1) We will select white light because it will absorb green light and reflects other colours. 

(2) We will select a destarched plant because destarching ensures that any starch present after the experiment has been formed under experimental conditions. 

(b) (i) Reflex Action: Reflex action is an automatic, quick and involuntary action in the body brought about by a stimulus. Reflexes are of two types : 

(1) Simple (natural) reflexes and 

(2) Conditioned (acquired) reflexes. 

(ii) 

(1) DNA: Deoxyribose Nucleic Acid. 

(2) AIDS: Acquired Immune Deficiency Syndrome. 

(iii) (1) Blinking: Simple Reflex. 

(2) Cleaning of table: Voluntary Action. 

(3) Playing on Keyboard: Conditioned Reflex. 

(4) Salivation when food is put in: Conditioned Reflex.