Question

1. Contrast an autotroph with a heterotroph.

2. Name a couple organisms that undergo photosynthesis.

3. What is the function of the stomata?

4. Below is the chemical formula for photosynthesis:  

6 CO₂+ 12 H₂O + Light energy → C₆H₁₂O₆+ 6 O₂+ 6 H₂O

Where do the carbon atoms from carbon dioxide end up on the product side?

5. What are the two reactions that make up photosynthesis?

Answer 1

• Difference between an autotroph and heterotroph:

Autotroph	Heterotroph
1. Autrotrophs can make their own food for energy	1.Heterotrophs can't make their own food and depend on other organisms fro their food and to get energy from them
2. Autotrophs contain green pigment chlorophyll.	2. Heterotrophs do not contain chlorophyll.
3. Autotrophs take CO2 and release O2 in the environment.	3. Heterotrophs take O2 from the environment and release CO2 .
4. Examples: Green plant, bacteria and algae.	4. Examples: Herbivores, carnivores and omnivores.

• Organisms that undergo photosynthesis: Plants, Cyanobacteria, Green algae, Diatom, Phytoplankton, Euglena etc.

• Function of Stomata:

i) Stomata are small openings on the surface of leaves which helps in gaseous exchange i.e it opens during day time and allow the plants to take CO2 and release O2  in the environment for photosynthesis and closes at night.

ii) Stomatal openings help in transpiration.

iii) In dicotyledons large numbert of somata present at the lower side of the leaves in order to prevent excess water loss during day time and high temperature conditionn and prevent wilting of leaves. In monocotyledons same number of stomata is present on both side of the leaves.

4. The carbon atoms from the carbon dioxide is converted into organic compunds with the help of light energy in photosyntheis.

• The two reactions of photosynthesis is:

i) 2H2A + light 2A + 4[H] (Light reaction)

ii) 4[H] + CO2   (CH2O) + H2O (Dark reaction)

Therefore, the overall reaction of photosynthesis is: CO2  + H2A + light (CH2O) + 2A + H2O