Cell Biology - GCSE Biology Paper 1

What is a cell?

The building block that all living things are made from

Name organelles found in all eukaryotic cells

Nucleus, cytoplasm, cell membrane, mitochondria, ribosomes

Name 3 organelles not found in animal cells

Chloroplast, cell wall, large vacuole

What is the function of the nucleus?

Control cell activity/contains genetic material (DNA)

What is the function of the cell membrane?

Controls what substances go in and out of the cell

What is the function of the cytoplasm?

Where chemical reactions happen

What is the function of chloroplasts?

Carry out photosynthesis

What is the function of the cell wall?

Gives the cell shape and support

What is the function of ribosomes?

Where proteins are made (protein synthesis)

What are specialised cells?

Cells that have adapted (gained particular characteristics) in order to perform a particular job

What is the function of the sperm cell?

To fertilise an egg cell

What are the adaptations of a sperm cell?

Tail for movement, acrosome contains enzymes to break down egg cell membrane, lots of mitochondria to release energy to swim to egg.

What is the function of a nerve cell?

To carry electrical impulses

What are the adaptations of a nerve cell?

Many dendrites make connections to other nerve cells, and the fat -covered axon speeds up electrical impulses.

What is the function of a muscle cell?

To contract for movement

What are the adaptations of muscle cells?

Many mitochondria to release energy for muscle contraction

What is the function of a root hair cell?

To absorb water and mineral ions

What are the adaptations of the root hair cell?

Large surface area to maximise absorption of minerals and water, lots of mitochondria to release energy for active transport

What is the function of the xylem?

To transport water and dissolved ions

What are the adaptations of the xylem?

No top and bottom walls between cells to form continuous hollow tubes through which water is drawn up. Cells are dead, without organelles or cytoplasm, to allow free passage of water. Outer walls are thickened with lignin.

What is the function of the phloem?

To transport dissolved sugars

What are the adaptations of the phloem?

Made of living cells which are joined end-to-end and contain holes in the end cell walls (sieve plates) forming tubes which allow sugars and amino acids to flow easily through.

What is a tissue?

A group of similar cells which do a job

What is an organ?

A group of different tissues working together to do a job

What is a system?

A group of organs which work together to do a job

How do we calculate total magnification of a microscope?

Eyepiece magnification x objective lens magnification

What is the equation that links magnification, image size and actual size?

Image size = actual size x magnification

Define resolution

The ability to distinguish between two separate points that are very close together

Which type of microscope has a higher magnification and resolving power?

electron microscope

Why do specimens need to be stained prior to viewing under a microscope?

To see structures more clearly

Which objective lens should we start viewing with first?

Lowest power objective lens

Which focus knob should be used at low magnification?

Coarse focus knob

Which focus knob should be used at high magnification?

Fine focus knob

What is the key difference between eukaryotes and prokaryotes?

Prokaryotes have no nucleus

Where is the genetic material found in a prokaryotic cell?

In the cytoplasm

Give two examples of eukaryotic cells

Animal cells and plant cells

Give an example of a prokaryotic cell

Bacteria

What is a plasmid?

Small rings of DNA (often containing genes for antibiotic resistance) that are found in some prokaryotes

What is the function of the flagellum

Movement

Define diffusion

Movement of particles from an area of high concentration to an area of low concentration

What is cell division used for?

Replacement of old or damaged cells, growth of tissue.

What happens in stage 1 of the cell cycle?

Chromosomes (DNA) and cell organelles replicate.

What happens in stage 2 of the cell cycle?

Mitosis: 1 set of chromosomes move to each end of the cell

What happens in stage 3 of the cell cycle?

Cytoplasm divides to form 2 identical daughter cells

What is a stem cell?

An undifferentiated cell

Where are stem cells found in animals?

In embryos and in adult bone marrow

Where are stem cells found in plants

Meristem tissue is found at the tips of shoots and roots.

Why are stem cells so important?

They can differentiate into many different specialised cells so can be used to treat diseases

State three factors that affect diffusion

Concentration gradient, temperature and surface area

How does temperature affect the rate of diffusion?

At higher temperature particles have more kinetic energy, so move around more - rate of diffusion increases

State the relationship between the size of an organism and the SA:V

The bigger the size, the small the SA:V

Describe three adaptations of exchange surfaces

Large surface area, thin walls, good blood supply

Define osmosis

Movement of water from a dilute solution to a concentrated solution

What will happen to the mass of a piece of potato added to pure water? Explain why

The potato will gain mass as water moves by osmosis from the dilute solution to the more concentrated solution inside the cells of the potato

What will happen to the mass of a piece of potato added to a solution of salt/sugar? Explain why

The potato will lose mass as water moves by osmosis from the more dilute solution inside the cells to the more concentrated solution of salt/sugar

Define active transport

Movement of particles from an area of low concentration to an area of high concentration

Which forms of cell transport are active and which are passive?

Osmosis and diffusion are passive processes whereas active transport requires energy

Give an example of active transport in plants

Root hair cells use active transport to transport mineral ions from low concentration in the soil to a high concentration inside the cell

Give an example of active transport in animals

Cells in the small intestine use active transport to move glucose from a low concentration in the gut to a high concentration in cells and the bloodstream

What adaptation do cells that carry out active transport have?

They contain many mitochondria to release energy needed for active transport