Grana are absent in the chloroplast of algae.

Spirogyra does not have the ability to fix nitrogen from the atmosphere.

Boron is the element which is useful in the germination of seeds.

One of the major functions of magnesium (Mg) and iron (Fe) is the synthesis of chlorophyll.

K⁺ ions play a major role in controlling the opening and closing of stomata.

Green plants prepare their own food by using inorganic raw materials. This process takes place in the leaves containing chlorophyll, which is required for photosynthesis. Flowers are the organs of reproduction, fruits are the source of seeds for the next crop and thorns are the reduced leaves to prevent transpiration.

In parasitic mode of nutrition, the parasite lives in/on the body of the host and draws its nutrition from there.

Autotrophs are the organisms, which make their own food by using inorganic raw materials. The word 'autotroph' is derived from two Greek words: autos means 'self' and trophe means 'nutrients/nourishment'.

Plants get nitrogen from the soil by the activity of bacteria present in their root nodules, which convert atmospheric nitrogen into usable form. 

Two groups of organisms can live together in a mutual way, i.e. they benefit one in one respect and get benefited from the other in another respect. Such mode of sharing shelter and nutrition in two groups of organisms is known as symbiotic mode of nutrition.

Fungi feed on dead and decaying organic matter by releasing digestive enzymes from their bodies. Then, they absorb the digested and soluble form of food and derive their nutrition, which is known as saprotrophic nutrition.

Desert plants have leaves reduced to spines to prevent the excess loss of water by transpiration. So, the function of photosynthesis in them is taken up by the stem. Flower is the reproductive organ of the plant and roots, being underground, cannot receive sunlight and thus, cannot perform photosynthesis.

In the symbiotic relation of algae and fungi, both stay together, fungus providing shelter, water and minerals to the algae and in return, algae provide the prepared food to the fungi. So, the statement given in option (3) is incorrect.

Plants show response towards sunlight. Plant shoots grow towards sunlight and roots away from the sunlight, i.e. growth of leaves is dependent on sunlight.

Rhizobium enhancement, harvesting crops and spraying insecticide have nothing to do with the enrichment of the soil with nutrients. Manure is the organic substance, rich in humus and helps increasing the soil fertility.