What does differentiation mean?
Reveal answer
The process by which an unspecialised cell becomes specialised for a particular function, as different genes are switched on.
Key words: specialised · genes
2(b) CELL STRUCTURE · RECALL
2.5B Cell differentiation
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What is meant by the term differentiation?
Reveal answer
The development of specialised structures and functions in a cell.
Key words: differentiation
What is meant by the term specialised cell?
Reveal answer
A cell adapted to perform a particular function.
Key words: specialised cell
What is meant by the term division of labour?
Reveal answer
Different cells or tissues performing different tasks within a system.
Key words: division of labour
What is meant by the term adaptation?
Reveal answer
A feature that improves performance of a function in a particular context.
Key words: adaptation
Adaptation must be linked to function: for Red blood cell, give the adaptation and the functional advantage.
Reveal answer
Adaptation: Biconcave; packed with haemoglobin; no nucleus when mature. Functional advantage: Rapid oxygen exchange and high oxygen-carrying capacity.
Key words: Red blood cell
Adaptation must be linked to function: for Neurone, give the adaptation and the functional advantage.
Reveal answer
Adaptation: Long axon, branched dendrites and insulating myelin. Functional advantage: Carries impulses over distance and connects with many cells.
Key words: Neurone
Adaptation must be linked to function: for Ciliated epithelial cell, give the adaptation and the functional advantage.
Reveal answer
Adaptation: Motile cilia on its exposed surface. Functional advantage: Moves mucus containing trapped particles towards the throat.
Key words: Ciliated epithelial cell
Adaptation must be linked to function: for Sperm cell, give the adaptation and the functional advantage.
Reveal answer
Adaptation: Flagellum, many mitochondria, acrosome and haploid nucleus. Functional advantage: Reaches and fertilises an egg, contributing one chromosome set.
Key words: Sperm cell
Adaptation must be linked to function: for Root hair cell, give the adaptation and the functional advantage.
Reveal answer
Adaptation: Long projection, thin wall and many mitochondria. Functional advantage: Absorbs water and mineral ions efficiently.
Key words: Root hair cell
Adaptation must be linked to function: for Palisade mesophyll cell, give the adaptation and the functional advantage.
Reveal answer
Adaptation: Many chloroplasts; elongated and close to the upper leaf surface. Functional advantage: Absorbs light and carries out photosynthesis rapidly.
Key words: Palisade mesophyll cell
True or false, and why? “Differentiated cells have different genes.”
Reveal answer
False. Most have the same genome but express different combinations of genes.
True or false, and why? “Ciliated cells make mucus.”
Reveal answer
False. Goblet cells produce mucus; ciliated epithelial cells move it.
True or false, and why? “Root hair cells absorb all mineral ions by diffusion.”
Reveal answer
False. Mineral ions may be absorbed by active transport when moving against a concentration gradient.
True or false, and why? “Every adaptation is beneficial in every context.”
Reveal answer
False. A feature is advantageous for a particular function and may carry trade-offs.