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The model shows an interaction between immune cells, followed by formation of two cell types. What do labels P, Q and R represent? A. P: plasma cell; Q: glucose; R: helper T cell B. P: phagocyte; Q: antibody; R: red blood cell C. P: memory B cell; Q: lipid; R:…
Ripening pears release a gaseous signal that stimulates neighbouring fruit to ripen and to release more of the same signal. Which substance participates in this positive-feedback process? A. Abscisic acid B. Ethylene C. Insulin D. Gibberellin
After rapid travel across time zones, a person remains alert late into the local night. Which endocrine mismatch can contribute? A. Excess melanin released from the hypothalamus B. Release of oxytocin from the thyroid at sunset C. Loss of insulin release from…
A drug inhibits bacterial cell-wall synthesis but does not stop a virus multiplying inside a human cell. Why? A. The viral life cycle lacks the bacterial process targeted by the drug B. Antibiotics act only on multicellular parasites C. All viruses possess…
In this longitudinal flower diagram, which description identifies X and the reproductive organ to which it belongs? A. X is a stigma belonging to a carpel B. X is an ovule belonging to a stamen C. X is an anther belonging to a stamen D. X is a sepal belonging…
In an apple variety, pollen sharing the relevant incompatibility specificity with the maternal plant is rejected. What is a reproductive benefit of this mechanism? A. It prevents all changes in allele frequency B. It ensures that every ovule is fertilised by…
Which feature of auxin transport contributes to directional growth of a shoot? A. Efflux carriers are distributed asymmetrically in cell membranes B. Efflux carriers transport auxin only into cells C. Auxin pumps hydrogen ions exclusively into the nucleus D.…
Several hours after a meal, blood glucose falls below its regulated range. Which response helps restore the concentration? A. Pancreatic glucagon secretion stimulates breakdown of liver glycogen B. Pancreatic insulin secretion stimulates storage of glucose as…
A diploid primary spermatocyte in a mammal contains 40 chromosomes. After normal meiosis and differentiation, what is produced? A. Two sperm cells with 40 chromosomes each B. Four sperm cells with 20 chromosomes each C. Four sperm cells with 40 chromosomes…
Which event allows the maternal and paternal chromosomes to assemble on the first mitotic spindle after human fertilization? A. Both chromosome sets undergo a new meiotic division B. The pronuclear envelopes break down C. Paternal chromosomes are digested…