4.5-40.9

Question 1

What does gas exchange system contain

Answer 1

Trachea(windpipe,air moves through here)
Intercostal muscles(which relax and contract to ventilate lungs)
Bronchi (air from trachea moves here,lead to each lung)
Bronchioles (bronchi split into these air moves in)
Alveoli (bronchioles lead to alevoli,air sacs where gaseous exchange occurs)
Diaphragm (sperates the lungs from digestive organs,moves down causing inhalation)

Question 2

Adaptations of alevoli

Answer 2

Large surface area- each alveoulus is like a baloon. When you have a bunch of them together it is like having a bunch of balloons rather than one big one. There is more surface area this way for gas exchange
Thin walls- like capillaries, the wall of the alveoulus are very thin so that the diffusing gases can move in and put of the blood more quickly and easily.
Moist surface- if surface of alveoli is moist it makes it easier for gases to diffuse and prevents the inner surfaces sticking together.
Cappilary network- ensures a good blood supply. This blood takes away the oxygen that has diffused from the air inside the alveolus. This maintains the conecntration gradient that is needed for further diffusion.

Question 3

Transport in plants

Answer 3

Transpiration-Water leaves the plants by evaportaion as water vapour, through stomata
Translocation-Sugar sap is transported
up and down in Phloem vessels.
Transporation stream-Continuous columns of water. Water
is continued in the Xylem vessels

Question 4

Phloem vessel

Answer 4

Transports sugar made by photosynthesis from leaves to rest of plant. Includes transport to stem and roots where dissolved sugars are needed for making new plant cells. Also transported to storage organs for winter.
Phloem are living tissue where cells are alive. Translocation is movement of dissolved sugars.

Question 5

Xylem vessels

Answer 5

Xylem tissue is otber transport issue in plants. It carries water and mineral ions from soul around the plant to stem and leages. Mature xylem cell are dead.
Made of dead cells stacked end to end,reinforced with lignin

Question 6

Upper epidermis

Answer 6

On cell thick and covers the leaf like skin. The waxy cucticle is a layer of wax which protects the leaf from disease organisms. The cuticle is waterproof and helps prevent waterloss of water vapour from transpiration.

Question 7

Lower epidermis

Answer 7

One cell thick layer which contains pores called stomata. Each stomata is made from pair of guard cells. Allows gases and water avpour to diffuse in and out the leaf.

Question 8

Palisde mesophyll layer

Answer 8

Have a cylindrical shape which help light go
into the leaf. It is contained in chloroplasts which means photosynthesis mainly occurs here. Can move within cell where light intensity is greatest

Question 9

Spngy mesophyll layer

Answer 9

Irregular shaped cells with large air spaces between them and looks like a sponge. Have fewer chloroplasts than palisade cells meaning light intensity is less

Question 10

Guard cells

Answer 10

Stomata open and close in respone to changing conditions, wuch as light intensity,humidity and co2 concentration.

Question 11

Leaf vein

Answer 11

Water and salts enter leaf via
Xylem. Sugar from photoysnthesis passes out of the leaf via phloem.

Question 12

Light intensity increase or decrease?

Answer 12

If light intensity increases the rate of transpiration will increase-when more ligjy the plant will photosynthesise more. Means that the stonata eill open to let out CO2 in. Also means more water will be lost put stomata

Question 13

Temperature increase or decrease?

Answer 13

If temp increases, rate of transpiration will increase-Causes diffusion to occur more
rapidly and the rste of photosynthesis increases when tempretaure goes up. More stomata will be open fot gas exchange to occur

Question 14

Humidity increase or decrease?

Answer 14

If humidity increases, the rate of transpiration will decrease-Hot,dry conditions cause more water to evaporate from cells and diffusion occurs quicker. Water vapour diffuses more rapidly into dry air than into humid air because the concentration gradient is steeper

Question 15

Air movement/wind increase or decrease

Answer 15

If air movement increases the rate of transporation will increase-Increases the rate of evaportaion and also maintains steep conecntration gradient from the inside of leaf to the putside by removing water vour as it diffuses

Question 16

Controlling water loss

Answer 16

Two features that help plants reduce water loss in normal conditions is the waxy,waterproof layer (the cuticle) and and the stomata

The plant may wilt which id a protection mechanism against further water loss. Leaves collapse and hang doen. This greatly reduces the surface area available for water loss by evaportaion.

Question 17

Potometers

Answer 17

You can measure how much mass is lost based on the rate of tranpsiration of water leaving the plant. You can look at the mass start and the mas at then end in grams.

The polythene bag prevents evaporation from the soil so the only water loss
is from the plant.

-Another potomete gas a plant at one end of the ube and a ‘calibrated’npipette at the other end. If the
pipette is calibrated it means that it accurately shows volume (usually in ml)
- When setting this potometer up, a small air bubble is introduced into a narrow tube, called a
‘capillary’ tube. As the plant takes water in, the bubble will move along the scale.