R2101 2.2 Plant Tissue

Question 1

What are the 4 types of tissue?

Answer 1

vascular

epidermal

ground

meristematic

Question 2

Role of epidermis?

Answer 2

Single layer of cells with waxy layer called cuticle

A protective barrier against mechanical injury, water loss, and infection

Stomata allow gases to pass through

Guard cells regulate opening/closing of pores

Question 3

What/where is parenchyma tissue?

Answer 3

Composed of living cells that are thin-walled, adaptable, with differentiation, to various functions.

In the photosynthetic tissue in leaves (mesophyll), the pulp of fruits, and the endosperm of many seeds. Mainly in the cortex of stems (pith).

Actively involved in photosynthesis, secretion, food storage.

One of the three main types of ground, or fundamental, tissue, together with sclerenchyma (dead support tissues with thick walls) and collenchyma (living support tissues with irregular walls).

Question 4

What are vascular bundles responsible for?

Describe them.

Answer 4

Vascular tissues responsible for transport

Xylem (inside) – long, wide, open-ended cells; thick, lignified walls – transport water/dissolved minerals

Phloem (outside) – long, tube-like cells (sieve tubes) – sucrose and amino acids to roots, stems or flowers

Question 5

What is xylem?

Answer 5

A tissue which transports water and minerals from the roots upwards to the plant stem and leaves.

A physical process. Does not require energy.

Forms a continuous, hollow tube of dead cells strengthened by lignin.

Gives strength and support to the plant.

Question 6

What does phloem do?

Answer 6

Moves sucrose and amino acids produced by photosynthesis to where they are needed for:

• growing parts of the plant for immediate use
• storage organs such as bulbs and tubers
• developing seeds

Up and down the stem.

Requires energy as it is an active process.

Living cells.

Question 7

Sieve tubes

Answer 7

In phloem

Specialised for transport

No nuclei

Each sieve tube has a perforated end so its cytoplasm connects one cell to the next.

Sucrose and amino acids are translocated within the living cytoplasm of the sieve tubes.

Question 8

Companion cells

Answer 8

In the phloem.

One or more companion cells attached to each sieve tube provide the energy to transport substances.

A sieve tube is completely dependent on its companion cell(s).

Question 9

What/where is cortex tissue?

What is relationship with endodermis and casparian strip?

Answer 9

Unspecialized cells lying between the epidermis and the vascular tissues.

Cells may contain stored carbohydrates.

In roots and in some herbaceous stems the innermost layer differentiated into a cell layer called the endodermis. The cell walls of the endodermis possess a woody and corky band, called the casparian strip, around all the cell walls except those facing toward the axis and the surface of the root or stem.

Question 10

Where is ground tissue located?

Answer 10

It forms, among other things:

• the cortex and pith of stems
• the photosynthetic tissue layer within the epidermis of the leaves (mesophyll)
• the cortex of roots
• the mesophyll of leaves
• the pulp of fruits
• the endosperm of seeds