T2 - plant tissues, organs and systems

Question 1

True or False? Leaves are plant organs.

Answer 1

True. Leaves contain multiple tissues that work together to carry out photosynthesis.

Question 2

Where is epidermal tissue located in the leaves of plants?

Answer 2

Epidermal tissue is present on the upper and lower surfaces of leaves; the upper surface is the upper epidermis and the lower surface is the lower epidermis.

Question 3

What is the role of palisade mesophyll tissue?

Answer 3

The role of palisade mesophyll tissue is to carry out photosynthesis.

Question 4

True or False? Spongy mesophyll tissue contains some chloroplasts for photosynthesis.

Answer 4

True. Spongy mesophyll cells do contain chloroplasts. While most photosynthesis occurs in the palisade mesophyll tissue, some takes place in the spongy mesophyll layer.

Question 5

How is spongy mesophyll tissue adapted for gas exchange?

Answer 5

Spongy mesophyll tissue is adapted for gas exchange by the presence of air spaces between cells. This increases the surface area of the cells that comes into contact with the air, so enabling faster gas exchange.

Question 6

True or False? Xylem is the only type of vascular tissue found in plants.

Answer 6

False. Xylem and phloem are both types of vascular tissue found in plants.

Question 7

What is the role of guard cells in leaves?

Answer 7

Guard cells control whether the stomata in leaves are open or closed; this allows plants to reduce water loss via the stomata when water availability is limited.

Question 8

Where would meristem tissue be found in plants?

Answer 8

Meristem tissue is found in the growing tips of plant shoots and roots.

Question 9

True or False? The roots, stem and leaves together form a plant organ system.

Answer 9

True. The organ system that comprises the roots, stem and leaves enables the transport of substances around a plant.

Question 10

What is the role of root hair cells?

Answer 10

Root hair cells absorb water and minerals from the soil.

Question 11

True or False? Water is taken up from the soil by active transport.

Answer 11

False. Water is absorbed from the soil by osmosis while minerals are absorbed by active transport.

Question 12

How are root hair cells adapted to aid their function?

Answer 12

Root hair cells are adapted for absorption as follows: They have a large surface area, They contain mitochondria which release energy for active transport.

Question 13

Define the term xylem.

Answer 13

Xylem are vessels that transport water and mineral ions from the roots to the upper parts of plants.

Question 14

How are xylem vessels adapted to transport water around plants?

Answer 14

Xylem vessels are adapted for water transport as follows: they are hollow and have no end walls to allow continuous water movement, lignin strengthens xylem cell walls to prevent breakage of vessels.

Question 15

Define the term phloem.

Answer 15

The phloem is a tissue that transports dissolved sugars (sucrose) from the leaves to the rest of the plant (after photosynthesis).

Question 16

How is phloem tissue adapted for its role?

Answer 16

Phloem tissue is adapted as follows: it contains elongated tubes along which dissolved sugars can flow, the end walls of cells contain pores to allow passage of dissolved sugars.

Question 17

Define the term transpiration.

Answer 17

Transpiration is the loss of water vapour from the leaves of plants by evaporation.

Question 18

Describe the structure of stomata.

Answer 18

The stomata are pores in the leaf surface, surrounded by two guard cells.

Question 19

What is the role of the stomata and guard cells in transpiration?

Answer 19

The stomata and guard cells allow plants to regulate the volume of water lost during transpiration. When water availability is low the guard cells can close, reducing transpiration.

Question 20

Which four factors can affect the rate of transpiration in plants?

Answer 20

Four factors that affect the rate of transpiration are: Temperature, Humidity, Wind speed / air movement, Light intensity.

Question 21

What happens to transpiration rate as light intensity increases?

Answer 21

As light intensity increases the transpiration rate increases.

Question 22

True or False? Transpiration rate increases at high light intensity because the stomata close.

Answer 22

False. Transpiration rate increases with light intensity because the stomata open at high light intensities to enable gas exchange for photosynthesis.

Question 23

What happens to transpiration rate as temperature decreases?

Answer 23

As temperature decreases the transpiration rate decreases.

Question 24

True or False? Transpiration rate increases at higher temperatures due to the increased kinetic energy of molecules.

Answer 24

True. At higher temperatures water molecules have more kinetic energy and are more likely to diffuse out via the stomata.

Question 25

True or False? Transpiration rate increases as wind speed increases.

Answer 25

True. As wind speed increases the transpiration rate increases.

Question 26

Why does transpiration occur faster on a windy day?

Answer 26

Transpiration is faster on a windy day because wind blows water vapour away from the surface of leaves, maintaining a water vapour concentration gradient between the inside and the outside of leaves.

Question 27

How will putting a plant inside a plastic bag affect its rate of transpiration?

Answer 27

Putting a plant inside a plastic bag will decrease its rate of transpiration. This is because the bag will trap water vapour and raise humidity levels, decreasing the water vapour concentration gradient between the leaf and the surrounding air.

Question 28

True or False? Increasing humidity levels will increase the rate of transpiration.

Answer 28

False. Increasing humidity levels will decrease the rate of transpiration.

Question 29

Define the term translocation.

Answer 29

Translocation is the movement of dissolved sugar molecules through phloem tissue.