Question

Most of the Photosynthesis (80%) which takes place on this earth is carried out by
(a)Green plants on land
(b)Algae present in freshwater
(c)Algae present in ocean water
(d)Both B and C

Answer 1

Hint: Photosynthesis carried out by green plants and algae mainly is vital for all living organisms on earth as it provides oxygen as well as the energy required for life to sustain. It also contributes to the carbon cycle.

Complete answer:
Photosynthesis is mainly carried out by green plants and certain algae. But most of the Photosynthesis occurring on the Earth's surface is done by Algae. Therefore, they are the main source of food for all heterotrophs and the main producer of oxygen.

Additional Information: Photosynthesis in green plants-
The plants in our surroundings have green pigments named chlorophyll in their leaves which gives them the green color and helps absorb sunlight for Photosynthesis. In the presence of this photon energy, the green leaves produce glucose, and oxygen from water and carbon dioxide have been taken by the plant with the help of roots and leaves respectively. This photosynthesis is responsible for producing the oxygen content of the atmosphere and giving most of the energy necessary for living beings.
Besides green plants, algae and certain cyanobacteria can perform Photosynthesis and are together called photoautotrophs. In algae, Photosynthesis is carried out by chloroplast where chlorophyll is present. In-plant, algae, and cyanobacteria, sugars that are long-term energy storage are produced by the Calvin- cycle whereas some bacteria use other mechanisms like reverse Krebs cycle. In these bacteria, the chlorophyll pigments are present in the plasma membrane itself.
So, the correct answer is “Both B and C”.

Note: The algae that are mainly found in freshwater are green algae( Chlorophyta), red algae (Rhodophyta), blue-green algae (Cyanobacteria), and diatoms (Bacillariophyta). Marine algae include Cyanobacteria, diatoms, dinoflagellates, coccolithophores, etc. The diatoms, phytoplankton, and green algae can carry out photosynthesis. Some bacteria such as Cyanobacteria and anoxygenic photosynthetic bacteria also carry out this process.