Answer:
The correct answer would be 10.
The cell cycle can be divided into four phases namely gap 1 (G₁) phase , synthesis (S) phase, gap 2 (G₂) phase, and mitosis (M) phase.
DNA (deoxyribonuceic acid) content is only replicated and doubled in the S phase. However, the chromosome number remains the same. It can be explained as the number of chromosomes remains the same (2n) but number of chromatids doubles (4n) after S phase.
The number of chromatids restores to 2n in daughter cells after completion of mitosis.
Hence, if number of chromatids in metaphase was 20 i.e. 4n then the number of chromosomes (2n) would be 10.
Hence, 10 chromosomes or 5 pairs of chromosome would be present in the cell during its G₁ phase.
Answer:
The correct options are A and B
Explanation:
The two sentences that describe how meiosis differs from mitosis are - "Meiosis produces cells with half the chromosomes of the parent cell" and "Meiosis produces either male or female gametes."
Answer:
The correct option is d. In C3 plants the conservation of water promotes photorespiration.
Explanation:
Photorespiration is a metabolic pathway that leads to the loss of half the carbon fixed by photosynthesis, it occurs when the rubisco enzyme (which is responsible for carrying out the carbon fixation) of the Calvin cycle acts on oxygen instead of dioxide carbon. Photorespiration occurs in C3 plants, (considered C3, by the three carbon compound) when the CO2 concentration is reduced. The first step of the Calvin cycle is the fixation of carbon dioxide by rubisco, but at low concentrations of CO2, oxygen begins to be set in place. In conditions of moderate temperatures when C3 plants have enough water, the carbon dioxide supply is abundant and photorespiration is not a problem.
