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Consider three possible chemical signals in an animal. I. A cytokine released by an immune cell II. A pulse of cytosolic calcium ions III. A neurotransmitter released at a synapse Which can convey information in cell signalling? A. I only B. II and III only C.…
The schematic cross-section shows axons surrounded by concentric membrane layers. What function is associated with structure X? A. It provides insulation that permits faster impulse conduction along the axon B. It synthesizes neurotransmitter receptors in…
A liver cell reduces the amount of a particular enzyme after it is no longer needed. Which process limits further synthesis by removing the existing message? A. A nuclease degrades the enzyme-coding mRNA B. A protease converts the promoter into a silencer C. A…
Flaccid celery cells are transferred to a dilute solution whose solute concentration is lower than that of the cell contents. Their walls remain intact. Which initial response is expected? A. Water leaves and pressure potential rises B. Water enters and…
Which event is shared by mitotic and meiotic nuclear division? A. Homologous chromosomes must pair as bivalents in both B. The chromosome number is halved in both C. Chromatin becomes more condensed through DNA packaging with histones D. DNA is replicated…
Reciprocal crosses between lions and tigers can produce different adult hybrid sizes. Which explanation attributes this difference to inherited epigenetic information? A. The larger hybrid must have twice as many chromosomes B. All paternal alleles are…
A developing animal cell divides its cytoplasm very unevenly, leaving almost all of it in one product. Which process normally includes this pattern? A. Production of two equivalent daughter skin cells B. Binary fission of an intestinal bacterium C. Formation…
Erythrocytes are placed in a strongly hypertonic solution of an effectively non-penetrating solute. What is expected initially? A. They lose water and shrink B. They gain water until they lyse C. They increase their mass by synthesizing a cell wall D. All…
A survey records Betula pendula, Quercus robur, Betula pubescens and Quercus petraea. What can be deduced from these names? A. All four plants belong to one species B. Betula pendula and Betula pubescens share a genus C. Quercus robur and Betula pendula share…
A red fox (Vulpes vulpes) and a European rabbit (Oryctolagus cuniculus) occupy the same meadow. Which grouping necessarily includes both organisms there? A. One species B. One population C. One genus D. One ecological community