transport in plants

Question 1

xylem

Answer 1

a plant tissue made up of dead empty cells, joined end to end with no walls between them
run from roots to every leaf
transport water and mineral ions
helps support the plant
has thick cell wall, containing lignin

Question 2

structure of xylem

Answer 2

cell walls made of cellulose and lignin
keep vessels open to allow constant flow of water
in leaves lignin helps keep leaves flat and open to absorb sunlight
diameter- 15um-200um
narrow enough to keep column of water unbroken
wide enough to allow plenty of water to flow through

Question 3

phloem

Answer 3

plant tissue made up of living cells joined end to end
transports substances made by the plant like sucrose and amino acids

Question 4

vascular bundels

Answer 4

a group of xylem vessels and phloem tubes

Question 5

roots

Answer 5

root cap protects the root as it grows through the soil
the rest of the root is covered by epidermis cells
the root hair cells are formed from some of the epidermis cells

Question 6

root hair cells

Answer 6

absorb water and mineral ions from the soil
water moves in through osmosis
large suface do not live long, as the root grows the cells get damaged and replaced by new ones.

Question 7

transpiration

Answer 7

the loss of water vapour from the leaf
water moves up the xylem
reduced pressure at the top draws up water from higher pressure at the bottom
reduced pressure happens because water is lost by transpiration

Question 8

transpiration pull

Answer 8

transpiration pull is caused by loos of water vapour through trnaspiration
this causes a lower pressure at teh top of the system drawing up the water.

Question 9

how can we measure transpiration

Answer 9

using a potometer- an instrument for measuring the amount of water a plant loses through transpiration

Question 10

factors that affect transpiration

Answer 10

higher temp- greater kinetic energy of particles= faster evaporation
wind= water vapour is quickly moved away from the leaf. this leaves a constant diffussion gradient, becuae there is less outside than inside the leaf
humidity decreases the rate of transpiration because the gradient of water vapour is higher outside the leaf or the same amount

Question 11

translocation

Answer 11

movement of sucrose and amino acids in the phloem from sources to sink

Question 12

source

Answer 12

part of the plant that releases sucrose amino acids usually the leaves

Question 13

sink

Answer 13

part of the plant that uses or stores amino acids, sucrose. usually roots and flowers, the roots may store some sucrose as starch and flowers use sucrose to make fructose