Question

HSK pathway is also known as
A. ${C_3}$ cycle
B. ${C_4}$ cycle
C. ${C_2}$ cycle
D. None of the above

Answer 1

Hint: HSK pathway stands for hatch slack kortschak pathway. This is a metabolic pathway, a cyclic process that occurs in chloroplasts. Fixation of carbon dioxide is done in this pathway in plants.

Complete answer:
HSK pathway is named after the scientists who introduced this, HSK states hatch slack kortschak pathway. Burr and Kortshak determined first by their experiments about this pathway and later on M.D. Hatch and C.R. Slack gave its detailed deep description.
It is a photosynthetic process in few plants and is one out of the other three processes that helps in carbon fixation in few plants. It is basically the step 1 in extracting carbon from carbon dioxide so that we are able to use it in sugar and other biomolecules.

> Option A- ${C_3}$ cycle: Another name for ${C_3}$ cycle is Malvin – Calvin cycle and commonly known as calvin cycle. This process converts carbon dioxide and ribulose bisphosphate into two molecules of 3-phosphoglycerate. Plants that survive on ${C_3}$ fixation are called as ${C_3}$ plants.

> Option B- ${C_4}$ cycle: ${C_4}$ cycle is another name of HCK pathway. ${C_4}$ plants have a special feature that is Kranz anatomy due to this carbon dioxide fixation in these plants is very efficient. These plants are known as ${C_4}$ plants because the first product formed of carbon fixation is a 4 compound molecule not a 3 carbon compound. These plants are found in hot, dry climates and produce higher energy than ${C_3}$ plants.

> Option C- ${C_2}$ cycle: It is light dependent oxygen uptake and release of carbon dioxide that occurs in photosynthetic organisms and is known as photorespiration. It is known as an oxidative photosynthetic carbon cycle.

Hence, the correct answer is option (B).

Note: Kranz leaf anatomy is a characteristics leaf anatomy in ${C_4}$ plants, in this kind of anatomy vascular bundles are surrounded by layers of cells; the inner ring or inner layer is called bundle of sheath cells and outer ring has mesophyll cells. The inner ring cells are different from those of outer ring cells as they contain starch rich chloroplasts lacking grana. The main function of kranz anatomy is to provide a site where we can concentrate $C{O_2}$ by avoiding photorespiration around RuBisCO.