plants

Question 1

why do plants need transport systems

Answer 1

-diffusion too slow to meet their metabolic needs
-substances need to moved over a long distance
-low surface area to volume ratio

Question 2

Describe the structure of xylem tissue

Answer 2

consist of dead cells. They have a thick, strengthned, imperamble lignified cellulose wall with a hollow lumen- they lack organelles- end of cells have disappeared, holes known as pits- movement

Question 3

describe the structure of phloem of phloem

Answer 3

connected end to end to form sieve plates- the sieve plates have pores in the to allow for movement -lack nucleus and organelles- each sieve element has a companion cell and it contains a nucleus and many mitochondria- companion cell connect to sieve through pores known as plasmodesmata

Question 4

what is the role of phloem

Answer 4

transport sugar and amino acids from leaves to rest of plant

Question 5

what are cotyledons

Answer 5

organs that act as food stores

Question 6

what are dicotyledonous plants

Answer 6

make seeds contain 2 cotylendous and have a series of transoprt vessels running this is known as vascular system

Question 7

water movement of a plant

Answer 7

water enters the plant by root hair by osmosis

Question 8

what are 4 factors affecting rate of transpiration

Answer 8

light intensity, humidity, tempreture, wind

Question 9

what is transpiration

Answer 9

the loss of water vapour from the stomata by evaporation

Question 10

how does light affect transpiration

Answer 10

more light causes stomata to open=increasing surface area for evaportation

Question 11

how does temp affect transpir

Answer 11

more temp-more kinetic energy- faster moving molecules-more evaporation

Question 12

affect of humidity on transpir

Answer 12

reduces water poetential gradient -water po more greater outside of plant

Question 13

how does wind affect transpir

Answer 13

increase water potential

Question 14

what is cohesion

Answer 14

water molecules attracted to each other forms a h bond -stick together -water moves up xylem in a continous column

Question 15

what is capilarity

Answer 15

when water molecules stick to other things - moves faster up

Question 16

explain the cohesion-tension theory

Answer 16

1. water vapours evaporates through the stomata on leaves. This loss of water volume lows pressure
2. Due to this loss of water more water is pulled up to replace it
3. Due to h bonds water is cohesive and there is a column of water within the xylem
4. water moleucles adhere and stick to the cell walls which helps water be pulled up
5. this creates tension and narrows the xylem.