support and movement

Question 1

why are hollow tubes useful in support

Answer 1

• structurally strong: load distributed over greater greater area
• resists bending

Question 2

turgor pressure

Answer 2

osmotic flow of water causes it to enter vacuole and pushes cell membrane against cell wall = turgid
helps plants to stand upright. without will wilt = plasmolysed

Question 3

what are the sections of the stem

Answer 3

epidermis (outside), cortex (inside), vascular bundles (within cortex), pith (centre)

Question 4

describe the pith

Answer 4

made from parenchyma(store and transport nutrients)
turgid = increased volume
only have primary walls so can exert pressure on other cells

Question 5

describe the cortex

Answer 5

made from collenchyma (acts as ECM around vascular bundles)

pliable = provides support and allows flexibility (useful e.g. wind)

Question 6

describe the vascular bundles

Answer 6

made of xylem and phloem

surrounded by sclerenchyma. has thick secondary wall: flexible and returns plant to original shape

Question 7

lateral roots

Answer 7

come of off primary root

absorption of water and mineral

Question 8

primary root

Answer 8

anchorage and stability

Question 9

describe a hydrostatic skeleton

Answer 9

e.g. earthworms
a capsule filled with fluid surrounded by 2 layers of muscle:
segmental contraction
-circular = elongate and narrow body
-longitudinal = shorten and thicken body
bristles help drive body forward = anchorage

Question 10

describe exoskeletons

Answer 10

e. g. molluscs and arthropods
- hard outer shell protects soft inside
- segmented body and jointed feet (thick apart from joints)
- muscles inside attach to skeleton
- prevents strength and mobility, lightweight
- created by mineralisation

Question 11

limitations of an exoskeleton

Answer 11

• size limiting: if too big would crush animal

- is dead: when animals grow must shed and make new = malting/ecdysis…potential vulnerability

Question 12

what are the 2 types of endoskeleton

Answer 12

bony

cartilaginous

Question 13

describe cartilaginous endoskeleton

Answer 13

thin, flexible, buoyant

• only support system without tubes
• weight supported by water = doesn’t need to resist gravity
• avascular (no blood vessels)
• diffusion needed to obtain nutrients = must be thin

Question 14

describe bony endoskeleton

Answer 14

• rigid=support
• starts as cartilage when embryo
• moved via muscles
• responds to exercise and increases in mass = evolutionary adaption

Question 15

describe bone structure

Answer 15

has central cavity with red (RBCs produced) and yellow (adipose) marrow: reduces weight and increases strength

• made from mineralised connective tissue with calcified ECM rich in type 1 collagen
• living cells within matrix and lining layers of bones = periosteum and endosteum
• arranged in tubes around artery = osteon