Chapter 9

Question 1

Why do plants need a transport system

give and example for a reason as well

Answer 1

To ensure that all cells get a high amount of nutrients

Plants need to transport substances against gravity

Question 2

3 features of the xylem and explain

Answer 2

pits allowing water to move sideways between water

supported with lignin for structural support

made with dead cells to optimise water uptake

Question 3

3 feature of the phloem and explain why

Answer 3

Sieve tube elements to transport sugars around the plant

Companion cells designed for active transport of sugars

Plasmodesmata allow flow of substances between cytoplasm of different cells

Question 4

Describe the structure and function of the vascular system in the roots

3 points

Answer 4

Consists of xylem and phloem

Xylem arranged in an X shape to provide resistance against force

Surrounded by endodermis

Question 5

Describe the structure and function of the vascular system in the stem

2 points

Answer 5

Xylem on inside of the bundle to provide support and flexibility

Layer of meristem cells that produce new xylem and phloem tissue when required

Question 6

Describe the structure and function of the vascular system in the leaves

2 points

Answer 6

Consists of xylem and phloem forms the midrib and veins

Involved in transport and support

Question 7

Define transpiration

2 points

Answer 7

The evaporation of water from the leaves of plant

occurs when the plant opens the stomata to exchange oxygen and CO2

Question 8

Name 3 factors which effect ROR of transpiration

Answer 8

Increased light intensity

Increased temperature

Waxy cutile prevents transpiration

Question 9

How can we measure transpiration rate apparatus

Answer 9

Potometer

Question 10

What is water potential

Give and example 2 points

Answer 10

The tendency of water to move by osmosis from high water potential to low

Pure distilled water has water potential of 0

Question 11

Why is water potential important in plants

Answer 11

Basis by which water moves to the areas it is needed within plants

Question 12

What is apoplastic pathway

Answer 12

Water moves through the cell walls and intercellular spaces by mass flow

Question 13

When can apoplatic pathway be used

Answer 13

Only until water reaches the casparian strip

Question 14

What is it meant by symplastic pathway

Answer 14

A method of osmosis through the root hair cell where water moves through the cytoplasm via plamodesmata

Question 15

How do you start symplatic pathway

Answer 15

Water must be actively transported into cells

Question 16

Explain cohesion tension theory

Answer 16

Water molecules form hydrogen bonds with each other causing cohesion so water can be drawn up the stem

Question 17

Give adaptations of xerophytes that allow them to live in dry conditions

3 points

Answer 17

Small rolled leaves

Thick waxy cuticle

Stomata often closed

Question 18

Give adaptations of hydrophytes the allow them to live in wet conditions

Answer 18

Stomata often open

Wide flat leaves

Air spaces for buoyancy

Question 19

Summarise the mechanism of translocation

4 points

Answer 19

Sucrose produced in leaves loaded into sieve tube via active transport

Lowers water potential causing water to move in from xylem

Assimilates move along the sieve tube towards areas of lower hydrostatic pressure

Sucrose can diffuse into surrounding cells where it is needed