PLANT TISSUES 12 MARCH 2014

Lesson Description

In this lesson we:

Identify the different types of plant tissue

Be able to relate the different structures with the different functions

Summary

Plant Tissue

TISSUE LOCATION STRUCTURE FUNCTION

Meristematic Apical – tips of roots and shoots

Lateral – sides of roots and stems

Vascular cambium – between xylem and phloem of dicots

Cork cambium – inside cork cells

Thin willed

Large nucleus

No intercellular spaces

Regular shape

Actively dividing – Mitosis

Produce new cells for

Growth in length and width

Replace worn-out or damaged tissue

Differentiate into different types of tissue

Epidermis Outer covering of roots, stems and leaves

Stems and leaves

Guard cells surrounding a stoma

Regular shape

Thin walled

No chloroplasts

No air spaces

Covered with a cuticle

Roots

Regular shape

No cuticle

Outgrows – root hairs

Protect deeper-lying tissue

Cuticle reduced loss of water vapour by transpiration

Guard cells control opening and closing of stoma, control loss of water vapour and gas exchange.

In roots help to absorb water from soil.

Parenchyma Forms bulk of roots, stems, leaves and flowers.

Irregularly shaped round, oval

Thin-walled, large vacuole

Large intercellular spaces

Lack chloroplasts

Packing tissue

Stores food as starch or sugars

Intercellular air-spaces allow water and gases to pass through.

Chlorenchyma In upper layers of leaves and stems

Palisade and spongy mesophyll of leaves

Parenchyma tissue with chloroplasts

Thin-walled, irregularly shaped with intercellular spaces.

Elongated upper layer – palisade layer

Manufactures food y photosynthesis.

Collenchyma In epidermis of young stems

Regular shape

No intercellular spaces

Corners of cells are thickened

Give support and strength to above-ground parts

Sclerenchyma Fibres

In epidermis or stems

Cap around vascular bundles of dicot stems

Sheath completely around vascular bundle of monocots

Stone cells in shells of nuts and hard parts of fruits

Fibres

Long with tapered ends

Thick- walled

Very small inner cavities

Stone cells

Small, oval, irregular cells

Extremely thick walls with lumens almost completely blocked.

Give mechanical support to plant.

Xylem Within veins of leaves, vascular bundles of stems and stele of roots

Vessels

Cylindrical cells

Cross walls perforated or absent

No cell contents – dead cells

Form continuous tubes from roots to leaves

Thick walls (lignin)

Lignin laid down to form patterns

Tracheids

Ends tapered

Have perforated cross walls

Fibres and parenchyma as described above.

Vessels and tracheids transport water and mineral salts from roots to stems and leaves

Give strength and support

Phloem Within veins of leaves, vascular bundles of stems and stele of roots

Sieve tubes

Cylindrical cells

Cross walls perforated to form sieve plates

Thin-walled cells

Contain strands of cytoplasm continuous with that of next cell

Living cells

Companion cells

Lie next to sieve tubes

Thin walled with well defined nucleus

Cross wall present

Fibres and parenchyma as described above.

Sieve tubes transport manufactures food from leaves to all parts of body

Companion cells probably control the activities of sieve tubes.

Diagrams

Parenchyma

Epidermal

Epidermal Tissue – Root Hair

Epidermal Tissue – Stomata

Collenchyma

Sclerenchyma

Xylem

Phloem

Test Yourself

Question 1

The chief food making tissue of a plant is called

A Chlorenchyma

B Cortex

C Phloem

D Epidermis

E Xylem

Question 2

In a stem, collenchyma cells are mainly found near the

A xylem tissue

B epidermal tissue

C phloem tissue

D chlorenchyma tissue

E pith

Question 3

Tracheids differ from vessels because they are

A in the phloem

B much smaller

C thickened with lignin

D only found in softwood trees

E also found in sclerenchyma

Question 4

An example of a cell thickened with extra cellulose is

A collenchyma

B parenchyma

C tracheids

D vessels

E sclerenchyma

Question 5

Root hair cells are …..

A not living because the wall is lignified

B concerned with the entry of gases into the plant

C able to open and close due to uneven thickening

D waterproof to stop water diffusing into the soil

E concerned with absorbing water and mineral salts for the plant.

Question 6

Most of the photosynthesis in a plant occurs in the

A spongy mesophyll

B guard cells of the stoma

C green cortex cells

D phloem of the leaf vein

E palisade mesophyll

Question 7

Which of the following is NOT found in phloem tissue?

A parenchyma

B collenchyma

C sieve tubes

D companion cells

E fibres

Question 8

Which of the following is not a feature of sclerenchyma?

A contains fibres

B may contain stone cells

C lignified walls

D living tissue

E used for support

Question 9

Phloem tissue is...

A found in vascular bundles.

B made up entirely of non-living cells.

C a tissue which only conducts nutrients by diffusion.

D found in leaves only.

Question 10

The cells shown in the diagram on the right can be found in

A Bananas and pears

B pears and apples

C Apples and guavas

D Guavas and pears.

Improve your Skills

Question 1

Study the diagram below and answer the questions which follow on Plant Tissues.

1.1. Name the plant tissues represented by letters A, B, C and D. (4) 1.2. Explain how plant tissue labeled B is structurally suited for its function. (5) 1.3. Draw a simple diagram to show what the upper epidermis of a leaf would look

like. No labels required. (3)

Question 2

The photographs/diagrams below show various conducting cells / tissues of a plant.

2.1 Which photograph/diagram (A to D) represents a xylem tracheid?

Give a reason for your answer. (2)

2.2 Two cells are shown in diagram B.

Which labeled cell in diagram A is a cross section of one of these cells? (1)

2.3 Give the main function of cell type 4 in diagram D, and state how you were able to identify the cell. (2)

2.4 Of what substance is the cell wall of: a.) cell 1, and that of b.) cell 3 made.? (2)

Links

Bozeman summary - https://www.youtube.com/watch?v=zHp_voyo7MY