2 - MZH - Specialised cells + their properties

Question 1

Squamous epithelia

Answer 1

Properties:

• Thin
• Covers exterior body surfaces in contact with outside world (e.g. lungs).
• High rate of diffusion across cells.

How the cells give tissue these properties?

• Cells very thin and flat.
• Tissue is one cell thick.

Question 2

Muscle

Answer 2

Properties:

Able to shorten so moves the bones it is connected to in relation to joints.

How the cells give tissue these properties?

-Long cells contain bands of protein fibres (actin and myosin) that slide over each other to change overall length of cell.

Question 3

Ciliated epithelia

Answer 3

Properties:

Cilia sweep away pathogens and dust containing mucus in lungs.

How the cells give tissue these properties?

• Goblet cells secrete mucous.
• Cilia beat rhythmically in same direction so mucus moves to back of throat where pathogens swallowed.

Question 4

Cartilage

Answer 4

Properties:

• Firm flexible connective tissue.
• Used to hold open tubes in lungs.
• Protects ends of joints.

How the cells give tissue these properties?

• Cells produce matric containing elastin + collagen.
• Elastin allows flexibility so can rebound after joints compressed.
• Collagen makes stiff so holds open airways.

Question 5

Xylem

Answer 5

Properties:

Route by which water is moved up a plant from intake in the roots.

How the cells give tissue these properties?

• Cells are dead, hollow and strengthened with lignin so more waterproof.
• Low flow resistance, aids capillary action.

Question 6

Plant epidermis

Answer 6

Properties:

• Creates layer round leaf.
• Prevents water loss, allows gas exchange for photosynthesis.
• Lets light through

How the cells give tissue these properties?

• Thin so light can pass through.
• Secretes waxy cuticle to prevent water loss.
• Contains pairs of guard cells to form stomata allowing gas exchange

Question 7

Phloem

Answer 7

Properties:

Route by which organic solutes (sugars) are moved from leaves to rest of plant.

How the cells give tissue these properties?

• Companion cells are metabolically active
• They load sugars into almost hollow sieve plate cells for transport due to changes in fluid pressure.