Biology - Topic 2 Cell Division and Stem Cells

Question 1

What is Diffusion?

Answer 1

Net movement of molecules from an area of higher concentration to an area of lower concentration.

Question 2

What is the Cell Membrane

Answer 2

An envelope that surrounds the cell and lets substances in and out

Question 3

What are Particles?

Answer 3

Everything is made of particles and in a liquid or a gas these are free to move around

Question 4

What is a Solution?

Answer 4

Something can dissolve in a liquid to make a solution. For example sugar can dissolve in water to give a sugar solution

Question 5

What is Oxygen used for?

Answer 5

This gas is needed by all living things for respiration. All cells need oxygen and oxygen is carried in the blood to all parts of the body

Question 6

What is Carbon dioxide used for?

Answer 6

This is a waste product of respiration and needs to be removed from tissues in the body. It is removed by the blood and breathed out of the lungs

Question 7

What is Blood Plasma?

Answer 7

The liquid part of the blood which contains water, sugar, salt and carbon dioxide

Question 8

What is a Concentration Gradient?

Answer 8

The difference in concentration between two solutions

Question 9

What is Surface area?

Answer 9

The area of the surface of something. E.g. The lungs have a very large surface area for gas exchange.

Question 10

What is the Small Intestine used for?

Answer 10

An organ in the lower part of your abdomen that absorbs food and nutrients from your food

Question 11

What are the Lungs used for?

Answer 11

Organs where oxygen diffuses into the blood and carbon dioxide diffuses out.

Question 12

Whatndo fish use gills for?

Answer 12

Fish have gills which are the exchange surface for oxygen to diffuse into the blood and carbon dioxide to diffuse out

Question 13

What is Osmosis?

Answer 13

The diffusion of water from a region of high water potential (dilute) to a lower water potential through a partially permeable membrane

Question 14

What is a Dilite solution?

Answer 14

A solution which has a lot of water in it and not much solute. E.g. Dilute squash is very weak

Question 15

What is a Concentrated solution?

Answer 15

A solution which doesn’t have very much water in it and a lot of solute. E.g. concentrated squash is very strong

Question 16

What is a Partially Permeable Membrane?

Answer 16

A membrane that lets some things through and not others. E.g. it lets water through but not sugar or salt molecules

Question 17

What is Active Transport?

Answer 17

The net movement of substances from a region of low concentration to a region of high concentration (against a concentration gradient). It requires input of energy.

Question 18

What are Villi and Microvilli?

Answer 18

These coat the small intestine and allow food to diffuse into the blood by having thin walls, a good blood supply and a LARGE SURFACE AREA

Question 19

What are Alveoli?

Answer 19

Tiny sacs in the lungs that have thin walls, a good blood supply and a large surface area for diffusion of oxygen in and carbon dioxide out

Question 20

Describe what happens in the alveoli

Answer 20

CO2 moves from the blood into the alveolus

Question 21

Factors which affect the rate of diffusion

Answer 21

• The difference in concentration
• temperature
  -surface area of the membrane

Question 22

Factors which increase the effectiveness of an exchange surface

Answer 22

• large surface area
• thin membrane for a short diffusion path
• efficient blood supply
• ventilation

Question 23

How to calculate percentage change in mass of potatoes?

Answer 23

(Change in mass / by original mass) x 100%

Question 24

Why is there no change in mass for some cylinders?

Answer 24

There is the same water potential both inside the cell and the surrounding solution.

Question 25

What is a passive process?

Answer 25

Does not require the input of energy

Question 26

What is an active process?

Answer 26

Requires energy in the form of ATP