R2101 2.2 Describe character and function of plant tissues

Question 1

What is tissue?

Answer 1

A collection of similar cells that group together to perform a similar function

Question 2

Simple tissues (5)

Answer 2

1, Protective - e.g. epidermis
2, Meristematic tissue - cambium
3. Packing tissue - parenchyma
4. Supporting tissue (cellulose) - collenchyma
5. Suipporting tissue (lignin) - sclerenchyma

Question 3

Character and function of epidermis (3)

Answer 3

1. Protects plant from water loss and damage
   2, Single layer of cells on outside of stem that has a waxy layer of cutin called the cuticle
   3, Stomata, controlled by guard cells, open and close to allow gases to pass through this layer

Question 4

Character and function of meristematic tissue (5)

Answer 4

1. Where new cells are created by cell division
2. Undifferentiated (unspecalised for a particular function)
3. Cuboid in shape with small vacuoles and large nucleus and many mitochondria
4. Apical meristems (lengthwish growth at roots and shoot tips)
5. Lateral meristems (widthwise growth)

Question 5

Character and function of parenchyma (7)

Answer 5

1. Mass of parenchyman cells maintain plant shape
2. Release energy through respiration
3. In some plants can act as food stores e.g. strach in potatoes
4. Many of these cells contain chlorophyll so can photosynthesize
5. Can undergo cell division to heal plants - useful when taking cuttings
6. Help plants in waterlogged condition via aerenchyma cells that create space and air channels betweem stem, roots and leaves assisting aerobic respiration.
7. Pith - central zone of the stem mainly made up of parenchyma cells

Question 6

What makes up the dicot vascular bundles? (3)

Answer 6

1. Xylem
2. Phloem
3. Cambium

Question 7

What is the support tissue in young plants?

Answer 7

Collenchyma
Cells thickened with cellulose

Question 8

What is the strengthening tissue found in stems, roots and leaves?

Answer 8

Sclerenchyma
Develops a secondary wall with lignin - eventually kills the cell nucleus leaving a dead cell

Question 9

Two forms of sclerenchyma

Answer 9

Elongated cells which form fibres e.g. hemp produces rope

Toughened gritty bodies called sclereids e.g. form part of nut shells

Question 10

What makes up vascular bundles in monocots? (3)

Answer 10

1. Xylem
2. Phloem
   3, Strength with sclerenchyma

Question 11

Xylem description

Answer 11

Consists of vessels which are short, wide cells with perforted end walls, heavily strengthend with lignin and strung end to end to make continuous tubes for conducting water throughout the plant.

Question 12

Primary water conducting cells in angiosperms

Answer 12

Xylem

Question 13

Only water conducting cells in conifers (gymnosperms)

Answer 13

Tracheids

Question 14

Whats is a tracheid?

Answer 14

Primitive conducting cells exsiting alongside xylem

Question 15

2 Main compoments of phloem

Answer 15

.1 Companion cells
2. Sieve tubes

Question 16

Function of companion cells in phloem

Answer 16

1. Live cells with nucleus
2. Thought to provide energy for the sieve tube cells

Question 17

Function of sieve tubes in phloem

Answer 17

1. Have no nucleus, but are not lignified
2. End walls of sieve tubes have sieve plates through which food is transported from cell to cell in the form of sugers

Question 18

How are moncot vascular bundles represented in the stem?

Answer 18

They are scattered thoughout the stem

Question 19

How are dicot vascular bundles represented in the stem?

Answer 19

They are arranged in a ring in the stem. The cambium will form new xylem and phloem, so that the bundles will eventually join up in the process of secondary thickening which allows woody growth.