What makes a cell in a complex multicellular organism specialised?
Its features are suited to a particular function, for example its shape or the abundance or arrangement of its cell structures.
AQA GCSE Combined Science: Trilogy (8464) — Biology — Higher · 4.1.1.3
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What makes a cell in a complex multicellular organism specialised?
Its features are suited to a particular function, for example its shape or the abundance or arrangement of its cell structures.
How should you explain a specialised cell’s adaptation?
Link a specific feature of the cell to how it helps the cell perform its function.
How does a sperm cell's tail help it reach an egg?
It enables the sperm to swim through fluid toward the egg.
How do mitochondria support sperm movement?
They carry out respiration, releasing energy for the tail to beat.
How does the acrosome help a sperm fertilise an egg?
This cap on the sperm head contains enzymes that digest the egg's outer layers, allowing the sperm nucleus to enter.
What does it mean that a sperm nucleus is haploid?
It contains one set of chromosomes, rather than the two sets found in body cells.
Why is it important that the sperm nucleus is haploid?
It combines with the egg's haploid nucleus to restore the normal diploid number in the fertilised egg.
What is a neuron specialised to do?
Carry electrical impulses between parts of the body.
How does a neuron's long axon help it carry impulses?
It allows an impulse to travel a considerable distance within one cell.
What do a neuron's branched extensions allow it to do?
Connect with other cells.
How do branches at a neuron's endings help it pass signals?
They enable it to pass signals to multiple target cells.
How does the myelin sheath affect impulses travelling along an axon?
It insulates the axon and increases the speed of impulses.
What are muscle cells specialised to do?
Contract and produce force.
What shape are muscle cells?
They are elongated.
How do contractile protein filaments allow muscle cells to shorten?
The filaments slide past one another.
How do the numerous mitochondria in many muscle cells support repeated contraction?
They release energy through respiration.
What do muscle cells working together in muscle tissue produce?
Movement of the body or structures within it.
What is the function of root hair cells?
To absorb water and mineral ions from the soil, supplying them to the rest of the plant.
How does a root hair cell's projection help it absorb substances?
Its long, hair-like projection provides a large surface area for absorption.
How does a root hair cell's thin cell wall help absorption?
It gives water and dissolved substances a short path into the cell.
By what process does water enter a root hair cell?
Osmosis.
How can a root hair cell absorb mineral ions when their concentration is lower in the soil than in the cell?
By active transport.
How do mitochondria support active transport in root hair cells?
They release energy through respiration.
What substances does phloem transport between parts of a plant?
Dissolved sugars and other organic substances.
How are sieve tubes formed?
Living sieve tube elements join end to end.
How do sieve plates allow sap to pass between sieve tube elements?
Their end walls have pores through which sap can pass.
How are mature sieve tube elements adapted to leave space for sap flow?
They lack a nucleus and have little cytoplasm.
How do companion cells support the active loading of sugars into sieve tubes?
They contain many mitochondria and supply energy for active loading.
In phloem transport, what is the difference between a sugar source and a sugar sink?
A source supplies sugars; a sink uses or stores them.