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What is osmosis ?

The movement of water molecules across a partially permeable membrane from a region I high concentration to low concentration

1

What is a partially permeable membrane ?

A membrane with very small holes in, only small molecules can pass through them

2

How does water move in and out of cells ?

Through osmosis. Human cells have a semi permeable membrane - cell membrane

3

What is tissue fluid ?

It is what surrounds the cells in the body, it supplies the cells with everything it needs - water, oxygen, glucose, etc.

4

What three ways can substances move ?

Diffusion
Osmosis
Active transport

5

What is an exchange surface ?

It is what substances have to pass through, in osmosis, diffusion and active transport, in life processes. Like partially permeable membranes

6

How are exchange surfaces adapted for maximum effectiveness ?

•They are thin so the substance only has to pass a short distance
•Large surface area so more substances can pass through
•Good blood supply

7

What has the structure of a leaf adapted to do ?

Let gases diffuse in and out of cells

8

How has a leaf adapted to optimise gas and liquid exchange ?

•It has air gaps so carbon dioxide can diffuse into cells
•Underside of leaf covered with stomata
•Water vapour and oxygen diffuse out through stomata
•Flat shape of leaf increases area of exchange

9

How do guard cells affect stomata ?

They control stomata. They close if the stomata is losing too much water. Without guard cells the plant would wilt.

10

What is the thorax ?

The top part of your body

11

What separates the thorax from the abdomen (lower body) ?

The Diaphragm

12

How does the air you breath get into your lungs ?

It goes down the TRACHEA and is split into two tubes called BRONCHI. Each BRONCHUS progressively becomes smaller into tubes called BRONCHIOLES. They take the air to ALVEOLI where the gas exchange takes place.

13

What is ventilation ?

The movement of air in and out of the lungs

14

What are the intercostal muscles ?

Muscles between ribs

15

How do you breath in ?

As air goes in, intercostal muscles and the diaphragm contract. The thorax volume increases which lowers pressure in the lungs which draws the air in.

16

How do you breathe out ?

The intercostal muscles and the diaphragm relax which increases the pressure in the lungs which forces air out.

17

What do artificial ventilators do ?

They help people to breathe

18

What are villi ?

They are projections that line the surface of the small intestine. The increase surface area to absorb as much food as possible into the blood.

19

How are alveoli specialised to maximise diffusion ?

•A large surface area
•A moist lining for dissolving gases
•Very thin walls
•Good blood supply

20

What is the job of the lungs ?

To transfer oxygen into the blood and to remove waste carbon dioxide from it. They have millions of alveoli which are like little air sacks where gas exchange takes place.

21

What are cells on the surface of a plant's root called and what do they do ?

Root hair cell. It sticks out into the soil which increases it's surface area. As a result they are great at absorbing water and minerals

22

How are minerals taken in to the root hair cells ?

Through active transport

23

When does active transport take place ?

When the concentration of a substance in the area you want the substance to go to is high, diffusion cannot take place. This is when active transport is needed

24

What does active transport need for it to happen ?

Energy

25

Where does active transport take place in the human body ?

One example is When glucose is taken from the gut into the blood

26

What does phloem transport ?

Food

27

How do phloems work ?

They transport food substances from the leaves to growing regions like shoots. They do this by allowing the dissolved sugars to pass through small holes in the end

28

What do the xylem tubes transport ?

They transport water and minerals from the roots to the stem and leaves.

29

What are xylem constructed out of ?

Dead cells joined end to end