GCSE Biology Cell Biology

What is the function of the nucleus?

Contains genetic material (DNA) and controls the cell’s activities

What is the function of the cytoplasm?

Jelly-like substance where most chemical reactions take place

What is the function of the cell membrane?

Controls what enters and leaves the cell (partially permeable)

What is the function of the mitochondria?

Site of aerobic respiration – releases energy (ATP)

What is the function of the ribosomes?

Site of protein synthesis

What is the function of the cell wall (in plant cells)?

Made of cellulose – strengthens and supports the cell

What is the function of chloroplasts?

Contain chlorophyll – site of photosynthesis

What is the function of the permanent vacuole (in plant cells)?

Filled with cell sap – helps keep the cell turgid / supports the plant

Name the main differences between animal and plant cells

Plant cells have a cell wall, chloroplasts and a permanent vacuole; animal cells do not

What is the formula for magnification?

Magnification = Image size ÷ Actual size

What are the units usually used when calculating magnification?

Image size and actual size must be in the same units (usually mm or µm)

What is resolution?

The ability to distinguish between two separate points (how much detail can be seen)

What is the main advantage of an electron microscope over a light microscope?

Much higher magnification and much higher resolution

What are the two types of electron microscope?

TEM (Transmission Electron Microscope) and SEM (Scanning Electron Microscope)

What is a disadvantage of electron microscopes?

Samples must be in a vacuum (so living specimens cannot be observed) and they are expensive

What is the order of size: cell, organelle, molecule, atom?

Atom < molecule < organelle < cell

What is a specialised cell?

A cell that has adapted to carry out a specific function

How is a sperm cell specialised?

Has a tail for swimming, lots of mitochondria for energy, and an acrosome containing enzymes to penetrate the egg

How is an egg cell (ovum) specialised?

Large with food stores in the cytoplasm and a protective outer layer that changes after fertilisation

How is a nerve cell (neurone) specialised?

Long axon to carry electrical impulses, myelin sheath for insulation, and branched endings (dendrites) to connect with other cells

How is a muscle cell specialised?

Contains many mitochondria for energy and protein fibres that can contract

How is a root hair cell specialised?

Long projection (root hair) increases surface area for absorption of water and mineral ions

How is a xylem cell specialised?

Hollow tubes with lignin for strength; no end walls so water can flow continuously

How is a phloem cell specialised?

Sieve tubes with pores and companion cells to help transport sugars

Why do specialised cells have different structures?

Structure is related to function (adaptations allow them to perform their job efficiently)

What is the difference between a light microscope and an electron microscope in terms of magnification?

Light microscopes typically magnify up to about ×2000; electron microscopes can magnify over ×2 000 000

What is 1 micrometre (µm) in metres?

1 µm = 1 × 10⁻⁶ m (or 0.001 mm)

What is the function of the cell wall in bacteria?

Made of peptidoglycan – provides support and protection (different from plant cell walls)

What do all living cells have in common?

Cell membrane, cytoplasm and genetic material (DNA)

Name three organelles found in both animal and plant cells

Nucleus, mitochondria, ribosomes (also cytoplasm and cell membrane)