Bio y9 2nd half - plants

Question 1

in Guard cells the stoma is open when…

Answer 1

there is light and an excess of water
this means the Guard cells are swollen / turgid

Question 2

in Guard cells the stoma is closed when…

Answer 2

it’s dark and when there’s a drought
this means the Guard cells are shrunken / flaccid

Question 3

cuticle

Answer 3

protects the leaf

Question 4

upper epidermis

Answer 4

Epidermal tissues cover the leaf letting light penetrate through

Question 5

palisade cell

Answer 5

contains lots of chloroplast’s to absorb lots of light energy carrying out photosynthesis

Question 6

Spongy mesophyll

Answer 6

irregularly shaped to have many air spaces between the cells for gases to diffuse easily and to reach all cells

Question 7

Lower epidermis

Answer 7

Has many stomata which allow gases and water vapour to diffuse
Protect the underside of the leaf

Question 8

Guard Cells

Answer 8

Surround this stoma on the underside of the leaf open and close the stoma to allow CO2 to get to the cells and oxygen to leave via diffusion. Also allows for some water movement.

Question 9

Root hair cells

Answer 9

narrow tubes with large surface areas​

large surface area to increase the rate of mineral ions absorption.

contain lots of mitochondria , which release energy from glucose during respiration in order to provide the energy needed for active transport.

Question 10

Xylem

Answer 10

Thexylemtransports water and minerals from the roots up the plant stem and into the leaves.
most of the cells that make up the xylem are specialized cells called vessels.

Question 11

Vessels

Answer 11

Lose their end walls so the xylem forms a continuous, hollow tube.
Become strengthened by a chemical calledlignin. The cells are no longer alive. Lignin gives strength and support to the plant. We call lignified cells wood.
Transport in the xylem is a physical process. It does not require energy.

Question 12

Phloem

Answer 12

Thephloemmoves food substances that the plant has produced by photosynthesis to where they are needed for processes such as:
growing parts of the plant for immediate use
storage organs such as bulbs andtubers
developing seeds.
Transport in the phloem is therefore both up and down the stem.

Question 13

Translocation

Answer 13

teansport of substances in the phloem

Question 14

Sieve tubes

Answer 14

specialised for transport and have nonuclei. Each sieve tube has a perforated end so itscytoplasmconnects one cell to the next.

Question 15

Transpiration

Answer 15

the evaporation slash loss of water from the leaves through the stoma, which causes water to be drawn up the plant

Question 16

Why is transpiration so important?

Answer 16

Evaporation of water cools plants
Water is a reactant in photosynthesis
Cells full of water support the plant
Water carries dissolved materials around the plant

Question 17

Factors affecting the rate of transpiration:

Answer 17

Temperature
Humidity
Wind
light availability

Question 18

How to measure the rate of transpiration

Answer 18

by using a potometer

Set up potometer in room temperature
*Position air bubble at 0mm
*Record position of bubble after 5 minutes
*Repeat steps 1-3 in other named temperature different to original
*Describe at least one control variable (such as wind, humidity, light intensity, carbon dioxide concentration
*Describe use of repeats at each temperature for reliability

Question 19

How do guard cells open and close stomata?

Answer 19

Potassium ions diffuse into the cells which increases the concentration of the solution inside guard cells
As the gold sales on now less dilute water moves in by osmosis
The additional water leads to the guard cells swelling unevenly because the thicker inner walls are less flexible than the thinner outer walls
the stoma opens due to this uneven swelling

Question 20

Light effect on the rate of transpiration

Answer 20

Transpiration increases in bright light because the stomata open wider to allow more carbon dioxide into the leaf for photosynthesis. More water is therefore able to evaporate.

Question 21

Temperature effect on the rate of transpiration

Answer 21

transpiration is faster in higher temperatures Because evaporation and diffusion is faster at higher temperatures

Question 22

Wind effect on the rate of transpiration

Answer 22

transpiration is faster in windy conditions because water vapor is removed quickly by air movement speeding up the diffusion of more water vapour out of the leaf

Question 23

Photosynthesis

Answer 23

a chemical reaction by which green plant cells produce glucose & oxygen from carbon dioxide and water using light energy

Question 24

Light intensity effect on rate of photosynthesis

Answer 24

Without enough light a plant cannot photosynthesise very quickly even if there is plenty of water and carbon dioxide. increasing the light intensity will boost the speed of photosynthesis and then the rate will become steady as something else is a limiting factor for example temperature or carbon dioxide concentration

Question 25

temperature effect on rate of photosynthesis

Answer 25

Increasing temperature increases rate of photosynthesis, until it reaches a certain temperature where it starts to decrease temperature. This is because the enzymes become denatured and can no longer catalyse the photosynthesis reaction.

Question 26

Carbon dioxide concentration effect on rate of photosynthesis

Answer 26

Sometimes photosynthesis is limited by the concentration of carbon dioxide in the air. even if there is plenty of light, a plant cannot photosynthesise if there is insufficient carbon dioxide. increasing the concentration of carbon dioxide will boost the speed of photosynthesis and then the rate will become steady as something else is a limiting factor, e.g., temperature or light intensity

Question 27

Use of glucose (sugars) for plants

Answer 27

sugars are soluble molecules that need to be transported (via phloem) to the parts of the plant that need it. It can also be used as energy, to make cellulose cell walls and to make proteins for plant growth and repair.

Plants use glucose for respiration. They cannot make it at night so it is
converted into insoluble starch – this is the main energy store of a plant.

Question 28

mineral ions

Answer 28

Mineral ions are found in low concentrations in the soil compared to inside the root hair cells, so they need to be taken in by active transport nitrates, phosphate’s, potassium and magnesium help plants grow root hair cells absorb them.

Question 29

Nitrates use

Answer 29

used to make amino acids for protein

Question 30

Phosphates use

Answer 30

used in respiration and to make DNA & new cell membrane

Question 31

Potassium use

Answer 31

used in respiration, photosynthesis and to make enzymes

Question 32

Magnesium use

Answer 32

used in photosynthesis

Question 33

photosynthesis equation

Answer 33

Question 34

Humidity effect on the rate of transpiration

Answer 34

Transpiration is slower in humid conditions because diffusion of water vapor out of the leaf is slower if the leaf is already surrounded by moist air - less steep concentration gradient

Question 35

companion cells

Answer 35

transport of substances in the phloem requires energy. One or more companion cells attached to each sieve tube provide this energy. A sieve tube is completely dependent on its companion cell(s)