Question

Which one can respire in the absence of oxygen?
A. Seeds
B. Leaves
C. Stem
D. Root

Answer 1

Hint: The respiration is of two types-Aerobic and Anaerobic. Here the term respiration is referring to cellular respiration, which can be aerobic or anaerobic. One of these options is a part of a plant that will be insulated from atmospheric or soil air reserve. That part would have the ability to respire anaerobically.

Complete answer:
Aerobic respiration is a very energy efficient type of respiration that is favored by most of the organisms. An important aspect of aerobic respiration is the gaseous exchange with the surroundings. Oxygen has to be taken in, aids in cellular respiration (in the electron transport chain), and Carbon dioxide has to be released as a by-product. However, under the circumstances of no or less oxygen availability, they adapt anaerobic respiration. There are different types of anaerobic respirations depending on the end product (alcoholic fermentation, lactic acid fermentation, etc.)
In the given options, Seeds are the ones that can respire in the absence of oxygen. The seed coats are very tough barriers that are intended to protect the seed from extreme conditions. But in doing so, it has compromised the ability of gaseous exchange with the surroundings. As you can imagine, seed germination is a large energy-driven process. So to compensate for lack of oxygen, germinating seeds adapt anaerobic respiration. This kind of respiration is conditioned predominantly by the internal factors of the seed, and thus no external oxygen is needed.
The rest of the options (leaves, stem, and root) depends solely on oxygenic respiration and will undergo cellular death under anaerobic conditions.

The correct answer is option (A) Seeds.

Note: In the given options, roots and seeds are submerged in the soil in their lifetime. So the prospect of anaerobic respiration will be present in one of these two. Since roots have many pores and a relatively mild cell wall compared to seeds, they can utilize the oxygen present in the soil. So, the natural conclusion is Seeds.