Lecture 10

Question 1

Name the parts of the root

Answer 1

•Epidermis
•Cortex
•Vascular tissues

Question 2

What is the dermal tissue of the root system called

Answer 2

Epidermis
•Outermost layer of cells, like the skin of the root

Question 3

What is the ground tissue system of the root system called

Answer 3

Cortex
•Tissue inside epidermis that stores starch and other substances for the growth of the root; it is made out of parenchyma tissue

Question 4

Write a short note on the vascular tissue system

Answer 4

•In most roots, the vascular tissues form a central cylinder, but in some monocotyledons they form a hollow cylinder around a central pith

Question 5

Function of the Xylem

Answer 5

•carries the water taken in by the root hairs and epidermis up the plant to the stems and leaves

Question 6

Function of the Phloem

Answer 6

•carries the food produced by the leaves down to the roots to be stored in the cortex

Question 7

Write a short note on the endodermis

Answer 7

•the inner boundary of the cortex; one cell layer thick; controls the movement of water and minerals into the xylem and phloem

Question 8

Write a short note on the Pericycle

Answer 8

•a layer found inside the endodermis which may produce lateral roots
•also produces vascular cambium in dicots

Question 9

What’s different about endodermis and cortex

Answer 9

the endodermis lacks air spaces and the cell walls contain suberin in a band (the Casparian strip) that extends around the radial and transverse cell walls, which are perpendicular to the surface of the root.

Question 10

What is the pericycle composed of

Answer 10

•parenchyma cells with primary walls but these may develop secondary walls as the plant ages.
•Lateral roots arise in the pericycle.

Question 11

Name the external root anatomy parts

Answer 11

• Root cap
• Region of cell division
• Region of elongation
• Region of differentiation or maturation

Question 12

Name the major zones of root development

Answer 12

• Region of cell division
• Region of elongation
• Region of differentiation or maturation

Question 13

Write a short note on the region of cell division

Answer 13

•this is where the cells start to divide through mitosis

Question 14

Where is the apical meristem located

Answer 14

Region of cell division

Question 15

Write a short note on the region of elongation

Answer 15

•in this area just above the apical meristem, cells become longer and wider
• This action helps to push the root tip through the soil

Question 16

Write a short note on the region of Maturation

Answer 16

•at this point, the cells become specialized, or
differentiated, taking on specific primary functions
• For example, the development of root hairs, xylem, phloem,

Question 17

Where does cell division occur

Answer 17

At the tip of the root

Question 18

When does root growth occur

Answer 18

• Root growth occurs when cells in the meristem extend in the elongation zone

Question 19

What is elongation driven by

Answer 19

• Elongation is driven by hydrostatic pressure within the cells pushing the root tip further down the soil profile

Question 20

Where do root hairs form

Answer 20

Maturation zone

Question 21

Which parts of the root are furthest from the root tip

Answer 21

The oldest parts

Question 22

Write a short note on the apical meristem

Answer 22

•found at the root tip, is where new cells develop
• It is covered by the root cap – protects it from damage as it passes through coarse soil particles

Question 23

In the apical meristem how many times do cells divide per day

Answer 23

Once or twice a day

Question 24

What does the transitional meristem arise from

Answer 24

The tips of roots and shoots

Question 25

What forms the epidermis

Answer 25

The Protoderm

Question 26

What forms the ground tissue

Answer 26

The ground meristem

Question 27

What forms the primary phloem and xylem

Answer 27

The Procambium

Question 28

What forms the vascular cylinder

Answer 28

Procambium

Question 29

What forms the cortex

Answer 29

Ground meristem

Question 30

What does the vascular cylinder contain

Answer 30

1. Xylem=transports water and soluble nutrients from roots to shoot
2. Phloem = transports sugars from photosynthesis to roots

Question 31

Write a short note on the region of maturation or differentiation

Answer 31

• root hairs develop as protuberances from epidermal cells
• increase the surface area for the absorption of water
• cuticle exists on root but not on root hairs

Question 32

Write a short note on root hairs

Answer 32

• Root hairs are outgrowths from the epidermis
•They have a high surface area:volume so increase the root surface area in contact with the soil
• Their capacity to absorb water and nutrients is huge, their small diameter
means they can fit between small pores
•They are short-lived (days), so die back and the older parts of the root would be hairless

Question 33

Write a short note on the root cap

Answer 33

• The root cap is a cone of cells which protects the meristem and secretes mucilage
• The root cap protects the root as it pushes through the soil
• Root cap cells are constantly sloughed off
• The mucilage provides an environment for bacteria and fungi which live in the rhizosphere (the immediate environment of the root)