Plant transport

Question 1

Characteristics of xylem 3

Answer 1

Carries water and mineral salts
Dead cells
One way

Question 2

Characteristics of phloem

Answer 2

Carries sugar and amino acids
Live cells
Bidirectional

Question 3

Packing off xylem and phloem in root

Answer 3

Centralised to anchor plant

Question 4

2 types of tubes in the xylem

Answer 4

Tracheids
Vessels

Question 5

Characteristics of tracheids 3

Answer 5

Narrower
Cells have perforated end walls
These cells provide support

Question 6

Characteristics of xylem vessels 4

Answer 6

Wider cells
Reduced or absent end walls= continuous tube
Main conducting tubes
Only in flowering plants

Question 7

What is the advantage of the xylem being made of dead cells

Answer 7

No cytoplasm, Easier for upflow of water

Question 8

Function of lignin

Answer 8

Provide mechanical strength
Prevent collapse
Support plant
Allow adhesion of water molecules

Question 9

Pits in xylem walls and function?

Answer 9

Areas of thinner lignin, allowing sideways movement of water through vessels

Question 10

Components of xylem

Answer 10

Vessels
Tracheids
Fibres
Parenchyma

Question 11

Structure and function of parenchyma

Answer 11

Living packing tissue, keeps all xylem/ phleom elements in place

Question 12

Function of xylem/ phloem fibres

Answer 12

ONLY provide support, no transport

Question 13

What causes the death of xylem cells

Answer 13

Deposition of lignin on cellulose cell walls makes them impermeable

Question 14

In what structure is lignin deposited

Answer 14

Rings or spirals

Question 15

Comparison points between xylem and phloem 4

Answer 15

Direction of flow
Product carried
Presence of end walls
Presence of lignin

Question 16

What must occur to allow the continuous movement of the transpiration stream

Answer 16

Column of water in xylem must be intact, no breaks or bubbles

Question 17

How is the affect of bubbles mitigated in the transpiration stream

Answer 17

Pits between adjacent vessels allow lateral movement of water, sk the column can bypass the bubbles

Question 18

4 cell types in phloem

Answer 18

Seive tubes
Companion cells
Phloem fibres
Phloem parenchyma

Question 19

Describe the organelles in seive tube elements 3

Answer 19

No nucleus
Few organelles
Only strands of cytoplasm

Question 20

What do the cell walls of the seive elements in phloem form

Answer 20

Seive plates

Question 21

Function of companion cells

Answer 21

Keep seive tube elements alive acting as their life support unit on their behalf

Question 22

How are the cytoplasm of seive tube elements and that of companion cells joined

Answer 22

By plasmodesmata

Question 23

Characteristics of companion cells 3

Answer 23

Dense cytoplasm
Several mitochondria and ribosomes
Very metabolically active

Question 24

Arrangement of xylem and phloem in stem

Answer 24

Peripheral to resist bending

Question 25

When do stomata close and why

Answer 25

At night when photo is not occuring In bright light bc is often accompanied by high temp After excessive water loss

Question 26

Outer most layer of a root+ structure

Answer 26

Epidermis: may have root hair cells to increase SA

Question 27

Adaptations of root hair cells

Answer 27

Progection to inc SA Many mitochondria and carrier proteins Cellulose cell walls freely permeable to water

Question 28

Cortex?

Answer 28

Layer of packing tissue between epidermis and endodermis

Question 29

Vascular bundle

Answer 29

Contains xylem and phloem and is lined with pericycle cells after the endodermis

Question 30

Casparian strip?

Answer 30

A band off waxy, waterproof suberin found in the well wall of the endodermal cells