B4- [Part 4]- Organising plants 🌱🪴

Question 1

TRUE OR FALSE: The leaf, is a plant organ?

Answer 1

True- the leaf is a plant organ. [and like any organ, it contains different tissues. ]

Question 2

What are epidermal cells found ?

Hint: upper, lower

Answer 2

• the top and the bottom of the leaf, are covered with a thin layer of very thin calls- known as epidermal cells.
• epidermal cells, form epidermal tissue.
• the upper epidermis is the top of the leaf; the lower epidermis is at the bottom of the leaf

Question 3

What is the role of the epidermis ?

Hint: surface

Answer 3

• the role of the epidermis, is to protect the surface of the leaf.

Question 4

What is the role of the upper epidermis ?

Hint: 💡

Answer 4

• the upper epidermis is transparent, which allows light
• and the upper epidermis, is also covered with a thin layer of oily material. [known as the waxy cuticle]

Question 5

What is the role of the waxy cuticle ?

Hint: reduce

Answer 5

• the role of the waxy cuticle, is to reduce the evaporation of water from the surface of the leaf.
• This helps to prevent the leaf from drying out

Question 6

What are the role of stomata ?

Hint: water vapour

Answer 6

• found at the lower epidermis, which has tiny pores:
• stomata allow carbon dioxide to enter the leaf and allow oxygen to diffuse out of the leaf
• ; stomata also help to control the amount of water vapour, that can pass out of the leaf.

Question 7

What is a second reason why transpiration an important process ? [3]

Answer 7

• the transpiration stream, transports dissolved mineral ions such as magnesium [which play important roles in the plant.]

Question 8

What is the role of the palisade mesophyll ?

Answer 8

• found at the top of the leaf, the palisade mesophyll consists of palisade cells.
• Palisade cells are packed full of chloroplasts, containing chlorophyll- chlorophyll absorbs the light energy, needed for photosynthesis.

Question 9

Where are spongy mesophyll located ?

Hint: air spaces

Answer 9

• located underneath the palisade mesophyll, the spongy mesophyll is full of air spaces.

Question 10

What are spongy mesophyll ? 🧽 [3]

Answer 10

• underneath the palisade mesophyll, the spongy mesophyll is full of air spaces. [think spongy- spongebob- air spaces]
• These air spaces allow carbon dioxide to diffuse from the stomata, through the spongy mesophyll, to the palisade cells.
• [oxygen also diffuses from the palisade cells, through the spongy mesophyll, to the stomata.]

Question 11

What does xylem tissue does ?

Hint: transports

Answer 11

• xylem tissue transports water from the roots, to the stem and leaves.
• some of the transported water, is them used in photosynthesis.
• the xylem also transports dissolved mineral ions: including magnesium- which is used to make chlorophyll.

Question 12

What does phloem tissue do ?

Hint: from the leaves

Answer 12

• phloem tissue transports dissolved sugars produced by photosynthesis, from the leaves, to the rest of the plant.
• these dissolved sugars can be immediately used. [e.g- glucose is used in respiration]; the dissolved sugars can also be stored [e.g- starch]

Question 13

What is translocation ?

Hint: other molcules

Answer 13

• translocation is, the movement of dissolved sugars and other molecules, through phloem tissue.

Question 14

What is transpiration ?

Answer 14

• transpiration is, the process of water constantly evaporating from the surface of leaves.

Question 15

What is the difference between translocation 🆚 transpiration ?

Answer 15

• translocation is, the movement of sugars and other molecules, through phloem tissue
• ; transpiration is, the process of water constantly evaporating from the surface of leaves.

Question 16

What’s a key fact about meristems ?

Answer 16

• meristem tissue contains stem cells, which can differentiate into any type of plant tissue.
• and meristems are found at growing tips [of a plant]: the tips of shoots and the tips of roots

Question 17

What is the process of the transpiration stream ? [4]

Hint: from cells, through, water passes, up the xyelm

Answer 17

• the process of transpiration begins with: the evaporation of water, from cells inside the leaf.
• water vapour then diffuses through the air spaces in the spongy mesophyll, and out of the leaf through the stomata.
• after that, water passes from the xylem, into the leaf- to replace the water that has been lost.
• and finally, water is drawn into the root hair cells, and up the xylem vessels to the leaf.

Question 19

What is one reason why transpiration an important process ?

Hint: transports

Answer 19

• transpiration is an important process, because it transports water to the leaf- which is required for photosynthesis. [because it is a reactant of photosynthesis]

Question 19

What is a third reason why transpiration an important process ?

Hint: weather

Answer 19

• a third reason why transpiration is important is because:
• the evaporation of water from the leaf cools the leaf down, especially in warm weather.

Question 20

What are the factors that affect the rate of transpiration ?

Answer 20

• the factors which affect the rate of transpiration are:
• 1) light intensity
• 2) temperature
• 3) air flow
• 4) and humidity

Question 21

How does temperature affect the rate of transpiration?

Answer 21

• temperature affects the rate of transpiration, because the rate of transpiration is greater at higher temperatures.
• This is because, evaporation is faster when temperatures are higher.

Question 22

How does humidity affect the rate of transpiration ?

Answer 22

• humidity can affect the rate of transpiration, because transpiration is faster under dry conditions [when the air isn’t humid, meaning humidity decreases the rate of transpiration]
• This is because evaporation takes place more quickly, under dry conditions.

Question 23

Explain how air flow affects the rate of transpiration

Answer 23

• air flow can affect the rate of transpiration, because the rate of transpiration increases in windy conditions.
• this is because wind removes any water vapour, therefore more water to evaporate.

Question 24

Explain how light intensity increases the rate of transpiration

Answer 24

• light intensity can increase the rate of transpiration, because the rate of transpiration increases, when the light intensity increases.
• This is because, high light intensity increases the rate of photosynthesis.
• Therefore the stomata can open, allowing carbon dioxide to enter
• and once the stomata have opened, water vapour can pass out of the leaf.

Question 25

What are the role of guard cells ?

Answer 25

• found on either side of the stomata, guard cells surround stomata and:
• the role of guard cells is to allow gas exchange, and control water loss within the leaf.
• this is because, when the light intensity is high [e.g- during the day], the guard cells swell and they change their shape.
• This then causes the stomata to open, allowing carbon dioxide to diffuse into the lead, which can be used in photosynthesis.

Question 26

What happens to guard cells in hot conditions ?

Answer 26

• in hot conditions, the plant closes its stomata, reducing water loss by transpiration.
• this now means the plant can’t photosynthesise.

Question 27

Why does the spongy mesophyll have air spaces ?

Answer 27

• the air spaces allow carbon dioxide to diffuse from the stomata, through the spongy mesophyll, to the palisade cells