Flashcards · 5090 · Topic 1

Cells flashcards

14 cards on Topic 1, subtopics 1.1 to 1.2. Pick a subtopic or study them all.

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Three structures in plant cells that animal cells lack: A cellulose cell wall, chloroplasts and a large permanent vacuole (containing cell sap).
Functions of the cell membrane, cytoplasm and nucleus: Cell membrane: controls what enters and leaves. Cytoplasm: site of chemical reactions. Nucleus: contains DNA and controls the cell.
Functions of mitochondria and ribosomes: Mitochondria: aerobic respiration. Ribosomes: protein synthesis.
How is a bacterial cell different from plant and animal cells?: No nucleus: its DNA is a circular loop free in the cytoplasm, often with plasmids. No mitochondria or chloroplasts. Its cell wall is not made of cellulose. (Bacteria do have DNA.)
Iodine solution and methylene blue as stains: Iodine solution: stains starch grains and cell walls; used for plant cells such as onion epidermis. Methylene blue: stains the nucleus and cytoplasm; used for animal cells such as cheek cells.
Magnification formula and its rearrangements: magnification = image size ÷ actual size. actual size = image size ÷ magnification; image size = actual size × magnification. Use the same units for both sizes.
A cell is drawn 60 mm long and is actually 0.03 mm long. Magnification?: 60 ÷ 0.03 = ×2000.

Red blood cell: adaptations and why: Biconcave shape and no nucleus, full of haemoglobin: a large surface area and more space for haemoglobin, so more oxygen is carried.
Root hair cell and palisade cell: adaptations: Root hair cell: long projection gives a large surface area for uptake of water. Palisade cell: many chloroplasts, near the upper surface, for maximum light absorption.
Xylem vessel and nerve cell: adaptations: Xylem vessel: hollow, dead and lignified, giving an uninterrupted water column and support. Nerve cell: long axon with branched ends, carrying impulses over a distance.
Tissue: A group of similar cells with a shared function (e.g. muscle).
Organ: Several tissues working together (e.g. stomach, leaf).
Organ system: Organs cooperating (e.g. digestive system).
Levels of organisation, from organelle to organism: Organelle → cell → tissue → organ → organ system → organism. (A leaf is an organ, not a tissue.)