Biology MCQs

Mitosis preserves chromosome number and supports growth and tissue repair.

Light reactions provide ATP and NADPH, while the Calvin cycle fixes carbon into organic molecules.

Aerobic respiration uses glycolysis, the citric acid cycle and oxidative phosphorylation to make ATP.

Enzymes catalyse reactions by lowering activation energy; conditions influence their structure and rate.

Negative-feedback systems detect deviations and activate responses that restore a regulated range.

Adaptive immunity forms antigen-specific memory cells, the basis of vaccination.

Matter cycles, but usable energy flows through ecosystems and declines at successive trophic levels.

Several evolutionary forces alter allele frequencies; drift is especially influential in small populations.

Cell membranes are phospholipid bilayers with proteins that regulate transport and signalling.

Mitosis preserves chromosome number and supports growth and tissue repair.

Meiosis forms haploid cells and generates variation through chromosome segregation and recombination.

DNA replication is semiconservative and uses complementary base pairing.