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One DNA coding-strand triplet changes from 5′-TCT-3′ to 5′-TGT-3′. All other triplets remain unchanged. Use the supplied coding-strand table. What follows from this substitution? A. Every later triplet is shifted by one base B. The encoded chain loses exactly…
Cell organization enables specialized reactions, and life cycles transmit inherited information. (a) Outline three structural differences between eukaryotic and prokaryotic cells. (b) Outline advantages of dividing a cell into compartments. (c) Explain sexual…
A researcher freezes a cell sample and splits membranes before electron imaging. Which feature is this technique particularly useful for examining? A. The nucleotide sequence of a chromosome B. The distribution of structures embedded within the lipid bilayer…
A typical yeast cell belongs to the fungi. Which combination describes its structures? A. Cell wall and nucleus present; chloroplast absent B. Cell wall absent; nucleus and chloroplast present C. Nucleus absent; chloroplast present D. Cell wall, nucleus and…
Which labelled set identifies structures typical of a photosynthetic plant cell but absent from a typical animal cell? A. A, B and E B. B, C and D C. C, D and F D. A, D and F
A sodium ion cannot readily cross the hydrophobic core of a lipid bilayer. Which pair of mechanisms can move it across a cell membrane? A. Osmosis and simple diffusion through lipid tails B. Channel-mediated diffusion and active transport through a pump C.…
Which structure is a functional cell organelle? A. The cellulose wall outside a plant cell B. A ribosome assembling a polypeptide C. The fluid cytosol as a whole D. A single actin filament in the cytoskeleton
A membrane contains aquaporin proteins. What role do they perform? A. They hydrolyse ATP to pump water against its potential gradient B. They attach water covalently to phospholipid tails C. They act only on the external membrane surface D. They provide…
Which list consists entirely of cell organelles? A. Cell wall, chromosome and cellulose fibre B. Ribosome, lysosome and Golgi apparatus C. Microtubule, plasma membrane and cell wall D. Collagen fibre, nucleus and chitin sheet
A spherical cell grows while keeping its shape and the same membrane permeability. How do surface-area-to-volume ratio and exchange capacity per unit cell volume change? A. Both increase B. The ratio increases but exchange capacity per unit volume decreases C.…