B6 | plant structures & functions

Question 1

how are root hair cells adapted at absorbing water and mineral ions from the soil?

Answer 1

large surface area means higher rate of osmosis of water and active transport of mineral ions

Question 2

what is active transport?

Answer 2

movement of mineral ions against the concentration gradient (from low to high) which requires energy

Question 3

what is transpiration?

Answer 3

movement of water/mineral ions upwards in the xylem from the roots to the leaves

Question 4

what is translocation?

Answer 4

movement of dissolved sugars and other substances up and down the phloem from leaves to roots

Question 5

how is the phloem adapted to its task?

Answer 5

small holes to allow flow between living cells

Question 6

how is the xylem adapted to its task?

Answer 6

thick walls for support and made of lignified dead cells

Question 7

which part of a leaf reduces water loss by evaporation?

Answer 7

waxy cuticle

Question 8

which part of leaf are packed with chloroplasts and are the main site of photosynthesis?

Answer 8

palisade mesophyll tissue

Question 9

which part of the leaf increases the rate of diffusion of gases through the leaf?

Answer 9

air space

Question 10

which part of the leaf is full of holes that allow gas exchange between the leaf and the air?

Answer 10

lower epidermis

Question 11

which part of the leaf is a transparent layer which allows light to pass through to the palisade cells?

Answer 11

upper epidermis

Question 12

which part of the leaf are kidney shaped cells which open and close the stomata?

Answer 12

guard cells

Question 13

which part of the leaf are tiny pores at the lower surface which allow diffusion of O2 and CO2?

Answer 13

stomata

Question 14

which part of the leaf are loosely packed cells which allow for interchange of gases during photosynthesis?

Answer 14

spongy mesophyll tissue

Question 15

how does CO2 enter the stomata?

Answer 15

diffusion

Question 16

what are the benefits of a plant being day neutral?

Answer 16

• plant can flower all year round
• flowering not limited to one period of time
• plant can flower for longer
• plant can flower at any time

Question 17

ways to measure light intensity without calculating it:

Answer 17

• light meter

- lux meter

Question 18

what does auxin control?

Answer 18

plant growth

Question 19

what does gibberellins control?

Answer 19

stem growth, flowering and seed production

Question 20

what does ethene/ethylene control?

Answer 20

ripening

Question 21

what effect do selective weed killers that contain auxin/gibberellin have on crops?

Answer 21

• selective weed killers are designed to target a specific plant
• hormones in the weed killer target the specific plant
• causing them to grow uncontrollably and die
• while leaving the other plants unaffected

Question 22

what does rooting powder contain and how is it used?

Answer 22

• contains auxins

- plant cuttings are dipped in the powder and planted

Question 23

3 advantages + 1 disadvantage of rooting powder:

Answer 23

• auxin makes roots develop rapidly
• you can get a large number of plants from the same plant
• no need to wait for plants to grow from seeds
• the new plants are all clones/genetically identical so there is a loss of genetic variation

Question 24

which hormones are used to make plants flower/seeds germinate early?

Answer 24

gibberellins

Question 25

how to produce seedless fruits:

Answer 25

• giberrelins added to unpollinated plant
• this means fruit will develop but seeds wont
• fruits are able to grow faster as less energy is spent on seed production