nutrition in plants

Question 1

how do plants absorb sunlight?

Answer 1

chlorophyll is a pigment in plants that absorbs sunlight

Question 2

what conditions are essential for photosynthesis?

Answer 2

• sunlight
• carbon dioxide
• chlorophyll
• suitable temperature
• water

Question 3

word equation for photosynthesis

Answer 3

https://images.app.goo.gl/F8os9Q98HWCZcCJi6

Question 4

how is carbon dioxide absorbed into the leaf?

Answer 4

carbon dioxide diffuses into the leaf via diffusion through tiny pores called stomata found mostly on the underside of the leaf

Question 5

factors affecting rate of photosynthesis

Answer 5

• light intensity
• carbon dioxide concentration
• temperature

Question 6

does light intensity increase the rate of photosynthesis?

Answer 6

https://drive.google.com/file/d/1_JruDktbAtes4QbvkrF6bIKHJw1hwksS/view?usp=drivesdk

Question 7

how does carbon dioxide concentration affect the rate of photosynthesis?

Answer 7

https://drive.google.com/file/d/1DlemmqNm3_VqtRNjRHusHjQGifWjiyZm/view?usp=drivesdk

Question 8

how does temperature affect the rate of photosynthesis?

Answer 8

https://drive.google.com/file/d/1FiMxL68xjMdya1VHSCHU9ZFM61zFJmMe/view?usp=drivesdk

Question 9

function of cuticle

Answer 9

• provides protection for the leaf by acting as a barrier against infection
• prevents excessive loss of water by evaporation as it forms a waterproofing layer

Question 10

function of upper epidermis

Answer 10

• closely packed cells that do not contain chloroplast and therefore do not photosynthesise
• small number of guard cells and associated stomata may be present

Question 11

function of palisade mesophyll

Answer 11

• two or three layers of vertically arranged cylindrical cells that contain a high amount of chloroplasts
• site for the highest rate of photosynthesis

the arrangement of the palisade cells in this layer, with their high concentration of chloroplast, maximises the use of available sunlight to manufacture food via photosynthesis

Question 12

function of spongy mesophyll

Answer 12

• loosely arranged, irregularly shaped cells with large intercellular air spaces between them
• contain chloroplasts and are able to carry out photosynthesis
• cells are used as storage sites for starch
• vascular bundles containing phloem and xylem tissues are found in this layer

Question 13

function of lower epidermis

Answer 13

• similar to the upper epidermis, it is covered by a layer of cuticle but contains a high number of guard cells and stomata

Question 14

function of guard cells

Answer 14

• bean shaped cells that provide openings (stomata) to the external environment for the purpose of gaseous exchange and transpiration
• guard cells also contain chloroplast and are able to carry out photosynthesis
• during daylight hours, guard cells produce glucose, increase amount of potassium ions in the cells and draw water in due to their lower water potential. the cells have thicker cell walls facing the stomatal openings and as they expand and become turgid, the stoma enlarges to allow more CO2 in for photosynthesis
• At night, guard cells do not photosynthesise. Thus, their water potential increases and water is lost from the cells. This causes the cells to become flaccid and decreases the size of the stoma, decreasing water loss.

Question 15

describe the intake of carbon dioxide

Answer 15

CO2 enters the leaf through the stomatal openings of the leaf by diffusion. This results in the formation of a concentration gradient with low CO2 in the leaf as compared to the surroundings. Thus, CO2 from the surroundings diffuses into the intercellular air spaces of the leaf.
- The CO2 in the leaf dissolves in the thin layer of water covering the mesophyll cells and diffuses into the cell for photosynthesis to occur.

Question 16

describe the intake of water and mineral salts

Answer 16

• water and mineral salts enter the leaf through the xylem tissue found within the vascular bundle
• both water and mineral salts are absorbed by the root hairs and transported to the leaf through the xylem tissue

Question 17

importance of photosynthesis

Answer 17

• as a food source for animals
• glucose can be converted into other products such as starch, fats and proteins
• maintains the balance of CO2 and O2 in the air

Question 18

function of petiole

Answer 18

holds leaf in position to absorb maximum light energy

Question 19

how is the lamina adapted to its function?

Answer 19

THIN lamina provides a short diffusion distance for gases and enables light to reach all mesophyll cells

BROAD lamina provides a large surface area for maximum absorption of light

Question 20

function of waxy cuticle on upper and lower epidermis

Answer 20

reduces water loss through evaporation from the leaf

Question 21

why are there more chloroplasts in upper palisade tissue?

Answer 21

more light energy can be absorbed near the leaf surface

Question 22

why are the veins containing xylem and phloem situated close to mesophyll cells?

Answer 22

xylem transports water and mineral salts to mesophyll cells

phloem transports sugars away from the leaf