Support and movement

Question 1

Describe one feature of parenchyma in the pith that aids in the support of plants.

Answer 1

They have thin cell walls which increases the volume of the vacuole, thus increasing the size.

Question 2

Describe one feature of collenchyma in the cortex that aids in the support of plants.

Answer 2

They have a primary wall with some thickening (e.g. corners) which allows them to be flexible and bend.

Question 3

Describe how the pith and cortex work together in plants.

Answer 3

Parenchyma press on collenchyma, forming a ‘pneumatic tire’.

Question 4

Describe one feature of vascular bundles that aids in the support of plants.

Answer 4

They are surrounded by sclerenchyma, a thick secondary cell wall, which provides rigidity and elasticity. This allows them to return to their original shape after deformation.

Question 5

What is the purpose of lateral roots?

Answer 5

Primarily absorption of water and dissolved minerals.

Question 6

What is the purpose of primary roots (‘tap roots’)?

Answer 6

Primarily anchorage and stability.

Question 7

Name 3 types of skeletal systems in animals.

Answer 7

• hydrostatic skeleton
• exoskeleton
• endoskeleton

Question 8

Describe the structure of hydrostatic skeletons in earthworms.

Answer 8

• contain septae/bristles
• capsule of fluid surrounded by 2 layers of muscle - circular and longitudinal
• fluid filled cavity acts as a rigid column on which muscles act

Question 9

Describe how the hydrostatic skeleton of earthworms enable them to move.

Answer 9

• circular muscles contract, elongating and narrowing the body
• longitudinal muscles contract, shortening and thickening the body
• segmental contraction of muscles and anchorage by bristles drives the body forwards - burrowing

Question 10

Describe some of the features of the exoskeleton.

Answer 10

• site for muscles attachment to create movement
• made of chitin - polysaccharide
• strong and light
• mineralisation makes it hard and protective
• thin and flexible at joints

Question 11

Describe some of the limitations of the exoskeleton.

Answer 11

• crushed
• do not grow with the body - molting (ecdysis)
• potential vulnerability until it hardens

Question 12

Describe some of the features of the cartilaginous endoskeleton.

Answer 12

• cartilage (may be calcified) must be thin
• light
• efficient and flexible

Question 13

Describe some of the features of the bony endoskeleton.

Answer 13

• rigid support against gravity
• develop from a cartilaginous skeleton
• levers which can be moved by muscles
  -dynamic and can respond to physical loading

Question 14

Describe some key features of the central (medullary) cavity in bone.

Answer 14

• reduces weight
• strength (resist compression and tension)

Question 15

Describe the microscopic structure of bone.

Answer 15

• living cells in a mineralised extracellular matrix
• arranged into columns around an artery = osteon