Structures of Plants (Chapter 7)

Question 1

What is the epidermis?

Answer 1

A continuous layer on the outside of the plant, one cell thick, that provides protection

Question 2

What is the epidermis covered with in stems and leaves?

Answer 2

A waterproof waxy cuticle which helps to protect the organ from drying out and from infection

Question 3

What does the epidermis have in laves?

Answer 3

Stomata, which are pores that allow entry of CO2 for photosynthesis

Question 4

What does the epidermis have in roots?

Answer 4

Extensions called root hairs to increase the surface area for absorption of water and mineral salts

Question 5

What is the parenchyma made up of?

Answer 5

Thin-walled cells which are used as packing tissue

Question 6

Describe 3 characteristics of the cells in the parenchyma

Answer 6

1) they are very metabolically active
2) may be used for storage of foods e.g. starch
3) when they are turgid, they help to support the plant, preventing wilting

Question 7

What do air spaces in the parenchyma allow?

Answer 7

Gas exchange

Question 8

How are water and mineral salts transported in the parenchyma?

Answer 8

Through the walls and living contents of cells

Question 9

What does the parenchyma form in roots and stems?

Answer 9

The cortex (outer region of cells)

Question 10

What does the parenchyma form in stems?

Answer 10

The pith (central region of stems)

Question 11

What does the parenchyma contain in leaves and what is it modified to form?

Answer 11

• It contains chloroplasts

- It is modified to form palisade and spongy mesophyll

Question 12

What is the collenchyma?

Answer 12

A modified form of parenchyma with extra cellulose deposited at the corners of cells, providing extra strength

Question 13

Where is collenchyma in leaves?

Answer 13

In the midrib of leaves

Question 14

Describe the endodermis

Answer 14

One cell thick and surrounds the vascular tissue (xylem and phloem) in stems and roots

Question 15

What is the mesophyll made up of?

Answer 15

Specialised parenchyma cells found between the lower and upper epidermis of the leaf

Question 16

What are the two types of mesophyll?

Answer 16

Spongy and palisade

Question 17

What do mesophyll cells contain and therefore what are they specilaised for?

Answer 17

They contain chloroplasts ∴ they are specialised for photosynthesis

Question 18

Where in the leaf are palisade mesophyll cells and why?

Answer 18

Near the upper surface of the leaf where they receive more sunlight ∴ they contain more chloroplasts than spongy mesophyll cells

Question 19

What does spongy mesophyll contain?

Answer 19

Many large air spaces between cells

Question 20

What is the pericycle?

Answer 20

A layer of cells just inside the endodermis and next to the vascular tissue

Question 21

Describe the pericycle in roots

Answer 21

One cell thick and new roots can grow from it

Question 22

Describe the pericycle in stems

Answer 22

Formed from sclerenchyma (a tissue with dead lignified cells for extra strength)