A cell whose genetic material (DNA) is enclosed within a nucleus . All animal and plant cells are eukaryotic.

A cell whose genetic material is not enclosed in a nucleus; instead the DNA is a single loop lying free in the cytoplasm. Bacteria are prokaryotic cells.

State the structures found in all cells, both eukaryotic and prokaryotic.

Cytoplasm Cell membrane Ribosomes Genetic material (DNA)

Besides a single loop of DNA, what extra genetic material may a bacterial cell contain?

Plasmids – small rings of DNA.

Prokaryotic cells are much than eukaryotic cells.

Prokaryotic cells are much smaller than eukaryotic cells.

Give the typical size of a eukaryotic cell and of a prokaryotic cell.

Eukaryotic cell: 10–100 µm Prokaryotic cell: about 1 µm

Controls the activities of the cell and contains the genetic material (DNA) .

What is the function of mitochondria ?

The site of most aerobic respiration , which releases (transfers) energy for the cell.

What is the function of ribosomes ?

The site of protein synthesis (where proteins are made).

The controls which substances enter and leave the cell.

The cell membrane controls which substances enter and leave the cell.

Which three structures are found in plant cells but not in animal cells?

Cell wall (made of cellulose) Permanent vacuole (filled with cell sap) Chloroplasts

What is the function of chloroplasts ?

The site of photosynthesis ; they contain the green pigment chlorophyll , which absorbs light.

What is the plant cell wall made of, and what is its function?

Made of cellulose . It strengthens and supports the cell.

What is the function of the permanent vacuole in a plant cell?

Filled with cell sap ; it helps to keep the cell firm ( turgid ) and supported.

A cell with a structure that helps it carry out a specific function .

Cells become specialised by a process called .

Cells become specialised by a process called differentiation .

How is a sperm cell adapted to its function?

Tail to swim towards the egg Many mitochondria to release energy for movement Acrosome containing enzymes to break down the egg's outer layer

How is a nerve cell adapted to its function?

Long (elongated) to carry impulses over large distances Dendrites to connect with other cells Fatty (myelin) sheath to speed up impulse transmission

How is a muscle cell adapted to its function?

Contains protein filaments that slide over each other to make the cell contract Many mitochondria to release energy for contraction

How is a root hair cell adapted to its function?

Long projection increases the surface area for absorbing water and mineral ions Thin wall for a short diffusion distance Many mitochondria to release energy for active transport

How are xylem cells adapted to transport water?

Hollow tubes (no end walls, no cytoplasm) allow water to flow freely Walls thickened with lignin to support the plant

How are phloem cells adapted to transport dissolved sugars?

Sieve plates (holes in the end walls) let sugars flow through Few subcellular structures so materials can move easily

The process by which a cell changes to become specialised for a particular function.

Why is cell differentiation important?

It produces different types of specialised cell , allowing a multicellular organism to carry out many different functions.

What happens to a cell as it differentiates?

It acquires different sub-cellular structures that enable it to carry out its specific function.

Compare when animal and plant cells differentiate.

Most animal cells differentiate at an early stage of development. Many plant cells keep the ability to differentiate throughout life .

In mature animals, what is cell division mainly restricted to?

Repair and replacement of cells.

True or False? Plant cells lose the ability to differentiate once they are mature.

False. Many types of plant cell keep the ability to differentiate throughout the life of the plant.

Why can an electron microscope be used to study cells in finer detail than a light microscope?

It has much higher magnification and resolution (resolving power), so more sub-cellular structures can be seen.

Write the equation used to calculate magnification .

Magnification = image size ÷ actual size

An image of a cell is 30 mm long and has been magnified × 3000. Calculate the actual size of the cell.

actual size = image size ÷ magnification = 30 ÷ 3000 = 0.01 mm (10 µm)

Before doing a magnification calculation, what must you do if the measurements are in different units?

Convert them into the same unit first. Remember: 1 mm = 1000 µm

Does magnification have units?

No – magnification has no units. It is written as, for example, × 100 or × 5000.

How have microscopy techniques developed over time?

First light microscopes used light and lenses to view cells and larger structures. Later electron microscopes used electron beams, giving much higher magnification and resolution and revealing many more sub-cellular structures.

An electron microscope has a higher magnification and higher than a light microscope.

An electron microscope has a higher magnification and higher resolution than a light microscope.

What is the aim of the microscopy required practical?

To use a light microscope to observe, draw and label a selection of plant and animal cells, including a magnification scale .

Why are stains such as methylene blue or iodine used when preparing a slide?

To make the cells and their structures show up more clearly under the microscope. Methylene blue stains cheek (animal) cells ; iodine stains onion (plant) cells .

Outline how to prepare a microscope slide of cells.

Place the specimen on the slide Add a drop of stain Lower a coverslip slowly to avoid trapping air bubbles

Which objective lens should you use first when focusing a microscope?

The lowest-powered objective lens.

What are the rules for a good biological drawing?

Use a sharp pencil with clear, unbroken lines No shading or colouring Label the structures and include a magnification scale

The coverslip should be lowered slowly to avoid trapping under it.

The coverslip should be lowered slowly to avoid trapping air bubbles under it.

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Cell Structure (AQA GCSE Combined Science: Trilogy: Biology): Flashcards

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FrontEukaryotes & Prokaryotes
Eukaryotic cell

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Cards in this collection (43)

Eukaryotic cell
A cell whose genetic material (DNA) is enclosed within a nucleus.
All animal and plant cells are eukaryotic.
Prokaryotic cell
A cell whose genetic material is not enclosed in a nucleus; instead the DNA is a single loop lying free in the cytoplasm.
Bacteria are prokaryotic cells.
State the structures found in all cells, both eukaryotic and prokaryotic.
Cytoplasm
Cell membrane
Ribosomes
Genetic material (DNA)
Besides a single loop of DNA, what extra genetic material may a bacterial cell contain?
Plasmids – small rings of DNA.
Prokaryotic cells are much than eukaryotic cells.
Prokaryotic cells are much smaller than eukaryotic cells.
Give the typical size of a eukaryotic cell and of a prokaryotic cell.
Eukaryotic cell: 10–100 µm
Prokaryotic cell: about 1 µm
A cell measures 0.0015 mm in length. Write this length in standard form.
1.5 × 10^-3 mm
How many micrometres (µm) are there in 1 millimetre (mm)?
1 mm = 1000 µm
Nucleus
Controls the activities of the cell and contains the genetic material (DNA).
What is the function of mitochondria?
The site of most aerobic respiration, which releases (transfers) energy for the cell.
What is the function of ribosomes?
The site of protein synthesis (where proteins are made).
The controls which substances enter and leave the cell.
The cell membrane controls which substances enter and leave the cell.
Which three structures are found in plant cells but not in animal cells?
Cell wall (made of cellulose)
Permanent vacuole (filled with cell sap)
Chloroplasts
What is the function of chloroplasts?
The site of photosynthesis; they contain the green pigment chlorophyll, which absorbs light.
What is the plant cell wall made of, and what is its function?
Made of cellulose.
It strengthens and supports the cell.
What is the function of the permanent vacuole in a plant cell?
Filled with cell sap; it helps to keep the cell firm (turgid) and supported.
Specialised cell
A cell with a structure that helps it carry out a specific function.
Cells become specialised by a process called .
Cells become specialised by a process called differentiation.
How is a sperm cell adapted to its function?
Tail to swim towards the egg
Many mitochondria to release energy for movement
Acrosome containing enzymes to break down the egg's outer layer
How is a nerve cell adapted to its function?
Long (elongated) to carry impulses over large distances
Dendrites to connect with other cells
Fatty (myelin) sheath to speed up impulse transmission
How is a muscle cell adapted to its function?
Contains protein filaments that slide over each other to make the cell contract
Many mitochondria to release energy for contraction
How is a root hair cell adapted to its function?
Long projection increases the surface area for absorbing water and mineral ions
Thin wall for a short diffusion distance
Many mitochondria to release energy for active transport
How are xylem cells adapted to transport water?
Hollow tubes (no end walls, no cytoplasm) allow water to flow freely
Walls thickened with lignin to support the plant
How are phloem cells adapted to transport dissolved sugars?
Sieve plates (holes in the end walls) let sugars flow through
Few subcellular structures so materials can move easily
Differentiation
The process by which a cell changes to become specialised for a particular function.
Why is cell differentiation important?
It produces different types of specialised cell, allowing a multicellular organism to carry out many different functions.
What happens to a cell as it differentiates?
It acquires different sub-cellular structures that enable it to carry out its specific function.
Compare when animal and plant cells differentiate.
Most animal cells differentiate at an early stage of development.
Many plant cells keep the ability to differentiate throughout life.
In mature animals, what is cell division mainly restricted to?
Repair and replacement of cells.
True or False?
Plant cells lose the ability to differentiate once they are mature.
False.
Many types of plant cell keep the ability to differentiate throughout the life of the plant.
Why can an electron microscope be used to study cells in finer detail than a light microscope?
It has much higher magnification and resolution (resolving power), so more sub-cellular structures can be seen.
Write the equation used to calculate magnification.
Magnification = image size ÷ actual size
An image of a cell is 30 mm long and has been magnified × 3000. Calculate the actual size of the cell.
actual size = image size ÷ magnification
= 30 ÷ 3000
= 0.01 mm (10 µm)
Before doing a magnification calculation, what must you do if the measurements are in different units?
Convert them into the same unit first.
Remember: 1 mm = 1000 µm
Does magnification have units?
No – magnification has no units. It is written as, for example, × 100 or × 5000.
How have microscopy techniques developed over time?
First light microscopes used light and lenses to view cells and larger structures.
Later electron microscopes used electron beams, giving much higher magnification and resolution and revealing many more sub-cellular structures.
An electron microscope has a higher magnification and higher than a light microscope.
An electron microscope has a higher magnification and higher resolution than a light microscope.
What is the aim of the microscopy required practical?
To use a light microscope to observe, draw and label a selection of plant and animal cells, including a magnification scale.
Why are stains such as methylene blue or iodine used when preparing a slide?
To make the cells and their structures show up more clearly under the microscope.
Methylene blue stains cheek (animal) cells; iodine stains onion (plant) cells.
Outline how to prepare a microscope slide of cells.
Place the specimen on the slide
Add a drop of stain
Lower a coverslip slowly to avoid trapping air bubbles
Which objective lens should you use first when focusing a microscope?
The lowest-powered objective lens.
What are the rules for a good biological drawing?
Use a sharp pencil with clear, unbroken lines
No shading or colouring
Label the structures and include a magnification scale
The coverslip should be lowered slowly to avoid trapping under it.
The coverslip should be lowered slowly to avoid trapping air bubbles under it.

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