Transport Systems

Question 1

3 points

why is there a need for transport systems

Answer 1

cells require essential substances such as nutrients and oxygen

in a multicellular organism, most cells lie far from the source of the essential substances

an efficient way is required for cells in multicellular organisms to obtain these substances

Question 2

4 points

how is water absorbed in a plant

Answer 2

root hair cell sap has a lower water potential than surrounding soil water and water moves in by osmosis

water moves from cell to cell down a water potential gradient until it reaches the cells surrounding the root xylem vessels

cells surrounding xylem vessels pump ions into xylem vessel by active transport, lowering water potential of vessels

water from surrounding living cells moves into xylem vessels by osmosis

Question 3

2 points

how are mineral salts absorbed in a plant

Answer 3

when concentration of ions is higher in surrounding soil solution than root hair cell, ions diffuse into root hair cell

when concentration of ions is higher in root hair cell than surrounding cell solution, minerals move into cell by active transport which requires energy

Question 4

2 points

how are root hair cells adapted for their functions

Answer 4

it is long and narrow to increase surface area to volume ratio

this increases the rate of absorption of water and dissolved mineral salts from soil into plants

Question 5

3 points

describe the vascular bundle

Answer 5

arranged in a ring around central region

phloem lies outside the xylem with a tissue called cambium between them

cambium cells can divide and differentiate to form new xylem and phloem tissues, giving rise to a thickening of the stem

Question 6

2 points

what are the functions of xylem vessels

Answer 6

conducts water and dissolved mineral salts from roots to stem and leaves

provides mechanical support for plant

Question 7

3 points

what is the structure of xylem vessels

Answer 7

made up of many dead cells fused together at the ends to form a long hollow tube

has continuous lumen with no cross-walls or protoplasm

lignin deposits in walls of xylem vessels

Question 8

2 points

how are xylem vessels adapted for their functions

Answer 8

hollow lumen enables water to move through easily

walls lignified to prevent collapse of individual vessels

Question 9

1 point

what is the function of the phloem

Answer 9

transports manufactured food (e.g. sucrose & amino acids) from leaves to other parts of plant

Question 10

5 points

what is the structure of the phloem

Answer 10

consists of mainly sieve tubes and companion cells

sieve tube cells are elongated cells that lack nuclei and have thin layers of cytoplasm

sieve tube cells joined end to end to form a column with sieve plates in between

sieve plates are cross-walls with many small sieve pores

companion cells are narrow, thin-walled cells with cytoplasm, nucleus and numerous mitochondria

Question 11

how is the phloem adapted for its function

Answer 11

companion cells have numerous mitochondria that release energy for the transfer of sugars into the phloem sieve tubes

Question 12

what is the use of the circulatory system

Answer 12

allows for quick transportation of nutrients and oxygen to all body parts so that the body can produce energy rapidly

Question 13

3 points

what does the circulatory system consist of

Answer 13

heart
blood vessels (arteries, veins, capillaries)
blood (transport medium)

Question 14

what is the function of veins

Answer 14

carries deoxgenated blood towards the heart

Question 15

what is the function of arteries

Answer 15

carries oxygenated blood away from the heart

Question 16

what is the function of capillaries

Answer 16

connects arteries to veins, site of exchange of substances

Question 17

6 points

how is blood transported through the heart

Answer 17

deoxygenated blood returns to the heart via the vena cava

right atrium contracts and blood flows into the right ventricle

right ventricle contracts and blood leaves through pulmonary arteries to lungs

oxygenated blood from the lungs flows to left atrium via pulmonary veins

left atrium contracts and blood flows into left ventricle

left ventricle contracts and blood flows through aorta to rest of body

Question 18

how does blood act as a transport medium

Answer 18

blood is a fluid tissue, consisting of plasma, red blood cells (erythrocytes), white blood cells and platelets

Question 19

2 points

what are the functions of plasma in blood

Answer 19

solvent for many substances

transports:
1) digested food from small intestine to other parts of body
2) carbon dioxide and other waste substances produced in body cells
3) other substances such as hormones

Question 20

3 points

how are red blood cells (erythrocytes) adapted to its functions

Answer 20

biconcave in shape:
- increases surface-area-to-volume ratio
- take in or release oxygen at a faster rate

contains haemoglobin:
- allows oxygen to be carried as oxyhaemoglobin

enucleate (nucleus absent):
- more room for haemoglobin

Question 21

3 points

what are the characteristics and function of white blood cells

Answer 21

kill bacteria or pathogens

colourless as they do not contain haemoglobin

have nucleus and larger than red blood cells

Question 22

2 points

what are the characteristics and function of platelets

Answer 22

fragments of cytoplasm (surrounded by membrane)

plays an important role in blood clotting

Question 23

3 points

how does the exchange of gases occur at the lungs

Answer 23

air is conveyed to the lungs by a system of branching ducts which end with alveoli (air sacs)

exchange of gases occurs at the alveoli in the lungs by diffusion

when our body cells respire, they make use of oxygen and produce carbon dioxide as waste substance