Chapter 8 - Transport in plants

Question 1

Define xylem and phloem

Answer 1

plant tissue made up of dead empty cells, joined end to end with no walls between them (tube)

Question 2

What are the 3 characteristics of the xylem?

Answer 2

• runs from roots through stem into every leaf
• transports water and mineral ions
• helps support the plant

Question 3

How are the xylem vessels and phloem arranged in the cross section of a root?

Answer 3

In a star (xylem in the middle) and the vessels on the side are the phloem

Question 4

How are the xylem vessels and phloem arranged in the cross section of a stem?

Answer 4

the phloem are outside of the xylem but each bundle is more seperate

Question 5

How are the xylem vessels and phloem arranged in the cross section of a stem?

Answer 5

the xylem vessels can be seen on top of the phloem

Question 6

What are the cell walls and xylem made of?

Answer 6

cellulose and ligrin that are very strong to keep the cell upright

Question 7

why does the structure of xylem keep the vessels open?

Answer 7

to allow constant flow

Question 8

what does ligrin do in the leaves?

Answer 8

keeps the leaves flat and open to absorb sunlight

Question 9

what is the approximate diameter of xylem?

Answer 9

15 µm - 200 µm

Question 10

Why is xylem narrow?

Answer 10

to prevent bubbles from forming

Question 11

What does the phloem transfer?

Answer 11

food - sucrose and amino acids

Question 12

Define vascular bundles

Answer 12

a group of xylem vessels and phloem tubes

Question 13

What does the root cap do?

Answer 13

protects roots as it grows through the soil

Question 14

What is most of the root covered by?

Answer 14

epidermis cells

Question 15

From where are root hair cells formed?

Answer 15

some of the epidermis cells

Question 16

What is the function of the root hair cells?

Answer 16

absorb water and mineral ions from soil

Question 17

How long do root hair cells live?

Answer 17

not very long

Question 18

How does the water get from the soil to the mesophyll in the leaves and where does it pass through?

Answer 18

soil → root hair cells → root cortex cells → xylem → mesophyll cells in leaves
all by osmosis

Question 19

How does water pass across the roots?

Answer 19

from cell to cell

Question 20

Why is water drawn up the xylem vesseles?

Answer 20

because transpiration is constantly removing water from the top of them

Question 21

Define transpiration

Answer 21

loss of water vapor from the leaves

Question 22

How is water vapor lost in a plant?

Answer 22

Water vapor moves up the root and stem in xylem vessels. Water evaporates from leaves through stomata

Question 23

What are the 3 characteristics of transpiration pull?

Answer 23

• caused by the loss of water vapor through transpiration
• causes lower pressure at the top of the system, drawing water up
• water moves up the xylem in one direction because of this

Question 24

Define potometer

Answer 24

an instrument for measuring the amount of water that a plant loses through transpiration

Question 25

What letter does a potometer look like?

Answer 25

U

Question 26

How does higher temperature affect the rate of transpiration?

Answer 26

greater kinetic energy of particles = faster evaporation

Question 27

What 3 factors affect rate of transpiration?

Answer 27

• wind
• temperature
• humidity

Question 28

How does wind affect photosynthesis?

Answer 28

is there is stronger wind, water vapor is pushed away from the leaf

Question 29

Why does humidity decrease transpiration?

Answer 29

because there is more water vapor outside of the leaf the inside than leaf

Question 30

Say if each of the factors that affect rate of transpiration is proportional of unproportional

Answer 30

• temp. (proportional)
• wind (proportional)
• humidity (unproportional)

Question 31

Define source

Answer 31

part of the plant that releases sucrose / amino acids: usually leaves (photosynthesis)

Question 32

Define sink

Answer 32

part of the plant that uses or stores sucrose / amino acids: usually roots and flowers

Question 33

What do roots store?

Answer 33

sucrose as starch

Question 34

What do flowers use sucrose for?

Answer 34

to make fructose