Aqa Igcse Biology. Key Facts Chapter 1

Front 1

What are living things made out of?

Back 1

Cells

Front 2

Name the parts of an animal cell

Back 2

Nucleus, cytoplasm, cell membrane, mitochondria and ribosomes

Front 3

What do plant and algal cells have that animal cells do not?

Back 3

A cell wall, chloroplasts, a permanent vacuole.

Front 4

What is the function of the nucleus?

Back 4

It controls the cells activities.

Contains genes on chromosomes that carry instructions for making protein.

Front 5

What is the function of cytoplasm?

Back 5

Where many chemical reactions take place

Front 6

What is the function of the cell membrane?

Back 6

It controls the movement of materials such as glucose and mineral ions in and out of the cell.

Front 7

What is the function of the mitochondria?

Back 7

Where energy is released during aerobic respiration.

Front 8

What is the function of the ribosomes?

Back 8

Where protein synthesis takes place

Front 9

What is the function of the cell wall?

Back 9

It is made of cellulose for support

Front 10

What is the function of chloroplasts?

Back 10

They contain chlorophyll for photosynthesis; the chloroplasts absorb light energy to make food.

Front 11

What is the function of the permanent vacuole?

Back 11

It contains cell sap

Front 12

Do bacterial cells have a cell membrane or a cell wall?

Back 12

They have both

Front 13

Do bacteria have a nucleus?

Back 13

no

Front 14

How is genetic material stored in a bacterial cell?

Back 14

It is found in the cytoplasm as a long strand of DNA

Front 15

What are plasmids?

Back 15

In bacterial cells, some genes are located in circular structures called plasmids.

Front 16

When can bacterial cells be seen with the naked eye?

Back 16

When they have multiplied to form a colony.

Front 17

How many cells are in an organism of yeast?

Back 17

One. It is a single celled organism

Front 18

Name the organelles in a yeast cell

Back 18

Nucleus, cytoplasm, membrane, cell wall, mitochondria

Front 19

How are yeast cells specialised?

Back 19

The can survive with little oxygen. They use aerobic respiration but can use anaerobic respiration (fermentation)

Front 20

How to yeast cells reproduce?

Back 20

Asexual budding. A new cell grows out of the original one.

Front 21

When can yeast cells be useful?

Back 21

In the production of ethanol and antibiotics and as a decomposer in food chains, but it may also break down stored food.

Front 22

Why might a cell have many mitochondria?

Back 22

If it needed lots of energy, e.g. in a muscle cell of a sperm cell.

Front 23

Why might a cell have many ribosomes?

Back 23

If it is making a lot of protein, e.g. gland cells which produce enzymes

Front 24

Why might a cell have a tail?

Back 24

So that it is able to move, e.g. sperm cells

Front 25

How are receptor cells specialised?

Back 25

They can detect stimuli, e.g. the cone cell in the eye is light sensitive and are specialised to connect with the optic nerve.

Front 26

Why might a plant cell have many chloroplasts?

Back 26

For photosynthesis, e.g. mesophyll cells of a leaf.

Front 27

How are root hair cells specialised?

Back 27

They increase the surface area of the root so that it can absorb water and mineral ions efficiently. Root hair cells are close to xylem tissue that transports water and mineral ions through the plant.

Front 28

What is diffusion?

Back 28

The net movement of particles from an area where they are at a high concentration to an area where they are at a lower concentration, down a concentration gradient.

Front 29

What happens to the rate of diffusion if the difference in concentration is increased?

Back 29

The rate is increased.

The larger the difference in concentration the faster the rate of diffusion.

Front 30

How do dissolved substances such as glucose and gases such as oxygen move in and out of cells?

Back 30

By diffusion.

Front 31

Give an example of diffusion in the body

Back 31

The diffusion of simple sugars and amino acids from the gut through cell membranes.

The diffusion of oxygen and glucose into the cells of the body from the bloodstream for respiration.

Front 32

What is osmosis?

Back 32

The movement of water molecules from an area of high concentration to an area of low concentration through a partially permeable membrane.

Front 33

What does it mean if two solutions are isotonic?

Back 33

The two solutions have the same concentrations

Front 34

What does it mean if a solution is hypertonic?

Back 34

It is more concentrated than the other solution

Front 35

What does it mean if a solution is hypotonic?

Back 35

It is more dilute than the other solution

Front 36

What is Plasmolysis?

Back 36

When plant cells are placed in hypertonic solutions in a lab, a lot of water leaves the cell. The vacuole and cytoplasm shrink, then the membranes pull away from the cell wall.

Front 37

What is active transport?

Back 37

The movement of substances from an area of low concentration to an area of high concentration, against the concentration gradient, through a partially permeable membrane.

Front 38

Where does the energy for active transport come from?

Back 38

Respiration

Front 39

Give an example of active transport in plants

Back 39

Root cells absorb mineral ions from dilute solutions in the soil by active transport.

Front 40

Give an example of active transport in humans

Back 40

Glucose can be reabsorbed in the kidney tubes by active transport

Front 41

What happens to the surface area to volume ratio as organisms increase in size?

Back 41

It decreases

Front 42

In multicellular organisms, many organs are specialised with effective exchange surfaces. What are the normal characteristics of an exchange surface?

Back 42

A large surface area and thin walls which give short diffusion distances.

Front 43

How are exchange surfaced adapted in animals?

Back 43

They will have a rich blood supply or, for gaseous exchange, will be ventilated.

Front 44

How are exchange surfaces in plants adapted?

Back 44

Plants have long thin roots with root hair cells in order to increase surface area for water absorption.

Plant leaves are flat and thin with internal airspaces and stomata to allow gases in and out of the leaves, for efficient gas exchange.

Front 45

What do the villi in the small intestine do?

Back 45

They provide a large surface area with an extensive network of blood capillaries close to thin walls so that the small intestine is well adapted as an exchange surface to absorb the small soluble products of digestion.

Front 46

How thin are the walls of the villi?

Back 46

Only one cell thick, so they provide a short diffusion distance.