Animal and plant cells Flashcards – AQA GCSE Combined Science: Trilogy (8464) — Biology — Higher

Which five structures are shared by plant and animal cells?

Cell membrane, cytoplasm, nucleus, ribosomes and mitochondria.

What does the cell membrane control?

The movement of substances into and out of the cell.

Where do many chemical reactions occur in a cell?

In the cytoplasm.

What is the role of the nucleus in a cell?

It contains genetic material and controls cell activities.

What do ribosomes make?

Proteins.

Where does aerobic respiration occur in a cell?

In the mitochondria.

Which three structures together distinguish a typical plant cell from an animal cell in a diagram or image?

A cell wall, chloroplasts and a large vacuole.

Which two structures found in typical plant cells are absent from animal cells?

Cell walls and chloroplasts.

What is the role of the plant cell wall?

It supports the cell and maintains its shape.

What is the role of chloroplasts in a plant cell?

They absorb light for photosynthesis.

What does the large vacuole of a plant cell contain?

Cell sap.

How does the vacuole help a plant cell?

It helps keep the cell firm.

When might the size or area of a sub-cellular structure need to be estimated from an image?

When an exact measurement is impossible or unnecessary, such as when the boundary is indistinct or irregular.

What can relate a measured image length to the corresponding actual length?

A scale bar or a known magnification.

What unit condition must be met when comparing image and actual lengths?

The lengths must use consistent units.

How can the relative linear size of structures be expressed?

As a ratio of their lengths.

What are two ways to estimate the area of a sub-cellular structure in an image?

Approximate it with a simple shape, or count grid squares, estimating partial squares.

How is the relative area of structures found?

Compare their areas measured on the same scale.

A linear scale factor converts an image length to an actual length. How is it used to convert image area to actual area?

Multiply the image area by the square of the linear scale factor.

What three factors affect estimates of sub-cellular size or area from an image?

Image quality, the structure’s shape, and the visible section of the structure.

How are the cell wall, cell membrane, cytoplasm and ribosomes arranged in a bacterial cell?

The cell wall surrounds the cell membrane; cytoplasm and ribosomes are inside.

What is the function of a bacterial cell wall?

It supports and protects the cell.

What is the function of a bacterial cell membrane?

It controls the movement of substances into and out of the cell.

What happens in the cytoplasm of a bacterial cell?

Many chemical reactions occur there.

What is the function of ribosomes in a bacterial cell?

They make proteins.

What form does a bacterial cell's main genetic material take, and where is it found?

It is circular DNA in the cytoplasm, rather than inside a nucleus.

What are bacterial plasmids?

Smaller circles of DNA that may also be present in a bacterial cell.

What is a bacterial plasmid?

A small circular DNA molecule found in some bacteria, separate from the main bacterial chromosome.

How does a plasmid replicate in relation to the bacterial chromosome?

It can replicate independently of the chromosome.

How can genes carried by plasmids spread between bacteria?

Plasmids can pass between bacteria, carrying their genes with them.

What can some plasmid genes give bacteria?

Useful properties.

Which types of cells have cell walls containing cellulose?

Plant and algal cells.

What is cellulose made of?

It is a carbohydrate made of long chains of glucose units.

How do cellulose chains strengthen a cell wall?

They form strong fibres that strengthen and support the wall.

How does the cell wall help maintain a cell’s shape?

It provides support that helps the cell maintain its shape.

What does the cell wall resist when water enters a cell?

Excessive expansion of the cell.