B1

Cells can  be prokaryotic or eukaryotic. All living things are made of cells. Eukaryotic cels are complex, animals and plant cells are eukaryotic. Prokyrotic cells are smaller and simpler. Bacteria are prokaryotic cells.The different parts of a cell are called subcllar structures. 

Name what most animals subcellular substances have and what they do: 

• Nucleus (contains genetic material, controls what cell does)
• Cytoplasm (where most of the chemical reactions happens)
• Cell memebrane (controls what goes in/out of cell)
• Mitrochondria (where most aerobic respiration happens which transfers energy that the cell needs to work)
• Ribosomes (protiens made in cell)

Plant cells have the same as what animals have however what else do they have: 

• Cell wall (supports the cell and strenghthens it
• Vacuole (contains cell sap)
• Chloroplasts (where photoshynthesis happens/food for plant)

Bacterial cells have the same structures as the oter cells but what else? 

- A single loop of DNA (no 'true' nucleus) 

- Plasmids (small rings of extra DNA) 

What do microscopes do? 

- Magnify things to make them look bigger. 

Microscopes have improved because of technolgy. 

What microscopes can be used to look at cells and why? 

- Light microscopes to look at a nucleus etc. 

Why are electron microscopes better than light microscopes? 

- They have a higher magnification. 

How do you work out the maginfiction of an image? 

- magnification = image size divided by real size. 

Name 2 specialised cells: 

1) A sperm cell  - takes the male DNA to the egg. 

2) Nerve cells - carry electrial signals around body.

What does a chromosone contain and what do they do? 

- Chromosones, contain genetic informtion. 

Cells divide true or false? 

- True. 

What is it called when cells divide? 

- Mitosis. 

Why do we need mitosis? 

- So that our organisms grown and develop. 

What are stem cells? 

-Stem cells differentnate into different types of cells. 

What are embroyonic stem cells? 

-could be used to replace faulty cells in sick people. 

Why do some people think stem cells are bad? 

- Because they belive embryonic cells should be left as it's taking an unborn baby's life.

What can stem cells do? 

-Clone, eg: produce identicle plants. 

What is 'diffusuion'? 

- Movements of particles from where there is lots of them to where there is fewer of them. The fancy way of saying it is: Diffusion is the spreading out of particles from an area of higher concentration to an area of lower concentration.

Where does diffusuion happen?

- In soulutions and gases. (For example, the smell of perfume diffuses through the air in a room)

What will give a faster diffusion rate? 

- Higher temps. 

What can fit through a cell membrane and what can't? 

- oxygen, glucose, amino acids, and water. Starch and proteins cant. 

What is 'osmosis'? 

-Movement of water molecules from less concentrated to a more concentrated 

What is active transport? 

- When substances need to be absorbed from lower concentration to higher.

Plant cells take in minerals and water using active transport as concentration of minerals is usally higher than soil around them.

Why do we need active transport? 

- To absorb our nutrients from food to survive.

What is a tissue? 

- Group of simelar cells that work together to carry out function. 

Tissues make up an organ to work together to perform a certain function. 

What is an organ system? 

- Group of organs working together to perform a function which breaks down and absorbs food.

What is enzyes? 

- reactions going on inside body which is cotrolled by enzymes. They are large proteins and speed up reactons. 

What does enzymes need? 

- the right temp and pH because it increses the rate. If gets too hot bond can break. 

How do I calculate the rate of reaction? 

Rate = 100 divided by time. 

What is the rate? 

- A measure of how much something chnages over time. 

Starch, protein and fats are what? 

-Biig molecules.

Why do digestive enzymes break these certain molecules? 

- Because they are too big so have to break into samller ones which then become easily absorbed in blodstream.