Question

Plants take carbon dioxide from the atmosphere mainly through their
A. Roots
B. Stem
C. Flowers
D. Leaves

Answer 1

Respiration is a chain of chemical reactions that helps all living organisms to synthesise the energy they need to sustain. That is a biological mechanism in which the air travels through the natural atmosphere and the tissues and cells of the organisms.

Complete Answer:
- Plants need oxygen to breathe, and the process produces carbon dioxide in return. Unlike humans and animals, plants do not have any unique gas exchange mechanisms, but they do have stomata located in leaves and lenticels found in stems that are actively engaged in gas exchange.
- Leaves, branches and roots of plants breathe at a low rate relative to humans and animals. Plants primarily take carbon dioxide from the atmosphere by their leaves. Stomata is a narrow opening on the surface of the leaves.
- Stomata are cells in the epidermis of tree leaves and needles that are used in the movement of carbon dioxide and water between plants and the atmosphere. Stomata consist of a pair of specialised epidermal cells referred to as guard cells. Stomata control the exchange of gas between the plant and the atmosphere and the regulation of the loss of water by adjusting the size of the stomatal pore.
- Roots absorb and carry water and nutrients to the stems. They are both anchoring and supporting the plant and preserving food. The root system is made up of primary and secondary roots.
- The stem of the plant links the roots with the leaves, helping to carry ingested water and nutrients to various areas of the plant. The stem also serves to transfer photosynthesis products from the leaves to the rest of the plant.
- The primary function of the flower is the reproduction since the flowers are the reproductive organs of the plant.

So, the correct option is D, leaves.

Note: During daytime hours, plants take carbon dioxide and emit oxygen by photosynthesis. At night, just about half of the carbon dioxide is released by respiration.