Glycolysis, the first step in the breakdown of glucose, takes place in which part of the cell?
- A.Cytoplasm
- B.Mitochondrial matrix
- C.Inner mitochondrial membrane
- D.Chloroplast stroma
Correct answer
Explanation
The correct answer is A, cytoplasm. Glycolysis, also called the Embden Meyerhof Parnas pathway, splits one molecule of glucose into two molecules of pyruvic acid in the cytoplasm, needs no oxygen and gives a net gain of two ATP along with two molecules of reduced NAD. Option B is wrong because the Krebs or citric acid cycle, not glycolysis, works in the mitochondrial matrix. Option C is wrong because the inner mitochondrial membrane holds the electron transport chain, where oxygen accepts electrons and most of the ATP is formed by oxidative phosphorylation. Option D is wrong because the stroma of the chloroplast is the site of the dark reaction of photosynthesis, the Calvin cycle, which builds sugar instead of breaking it. Since glycolysis is common to aerobic and anaerobic respiration, it is the most frequently asked step.
Read the full article: Plant Physiology: Transpiration, Transport and Respiration
Practice Questions
View allThe ascent of sap to the top of a tall tree is explained mainly by which force?
- A.Root pressure
- B.Capillarity alone
- C.Transpiration pull under the cohesion tension theory
- D.Active transport by xylem vessels
Show answer
Dixon and Joly explained that water molecules cling to one another by cohesion and to the xylem walls by adhesion, forming an unbroken column; evaporation from the leaf surface creates a suction at the top that pulls this column upward.
Read the full explanation →The loss of water in liquid form from the margins of leaves through special pores is called
- A.transpiration
- B.guttation
- C.bleeding
- D.imbibition
Show answer
It occurs through pores called hydathodes at the leaf margin or tip, usually in the early morning when the soil is moist, the air is humid and transpiration is low, so root pressure forces out drops of water with dissolved salts; Colocasia, grasses and tomato show it well.
Read the full explanation →Which tissue is responsible for the transport of prepared food in a plant?
- A.Xylem
- B.Phloem
- C.Parenchyma
- D.Sclerenchyma
Show answer
Its sieve tubes, helped by companion cells, carry sucrose and other soluble food from a source such as a mature leaf to a sink such as a root, fruit or bud, and the movement can be upward or downward.
Read the full explanation →The opening of stomata is brought about by the movement of which ion into the guard cells?
- A.Sodium
- B.Calcium
- C.Potassium
- D.Magnesium
Show answer
In light, potassium ions are actively pumped into the guard cells, their solute concentration rises, water enters by osmosis, the cells swell and because their inner walls are thicker they bend apart, opening the pore; when potassium leaves, the cells lose water and the pore closes.
Read the full explanation →Which instrument is used to measure the rate of transpiration in a cut shoot?
- A.Potometer
- B.Auxanometer
- C.Clinostat
- D.Respirometer
Show answer
Ganong's potometer and the simpler bubble potometer measure the water absorbed by a cut shoot in a given time, and since almost all of that water is lost as vapour, the reading is taken as the rate of transpiration.
Read the full explanation →