A Level Biology C7 Recap

What is the main photosynthetic organ of a plant?

• Root

• Stem

• Flowers

• Leaves

Which tissue(s) make up the vascular system in plants (choose all that apply)?

• Collenchyma

• Phloem

• Xylem

• Sclerenchyma

Answer explanation

The vascular system in plants refers to tubes and vessels, hence the xylem and phloem make up a plant's vascular system. Other cells exist outside of the vascular system.

Which of the following is TRUE regarding the vascular system in plants?

• Xylems carry photosynthetic products from the leaves

• Xylem sap can only move in one direction

• Phloem sap can move in two directions in the same tube

• Phloems carry water and inorganic ions from the roots

Which of the following is NOT a main organ involved in transport in plants?

• Flowers

• Roots

• Stem

• Leaves

Which cell type in plants has thicker cell walls with extra cellulose that provide support and strength and can often be found in the midrib of leaves?

• Parenchyma

• Collenchyma

• Endodermis

• Sclerenchyma

Label the following structures in the provided image of a plant stem.

a

b

c

d

e

Xylem

Vascular bundle

Phloem

Sclerenchyma

Parenchyma

Plants lose water vapour via stomata on the underside of leaves. This water then enters the environment. What is this process called?

• Evaporation

• Condensation

• Transpiration

• Guttation

Describe how transpiration creates a water potential gradient in the plant leading to the uptake of water by the roots from the surrounding soil.

Answer explanation

Following transpiration, the water potential in the leaf is reduced, which causes water to flow into the leaf from the xylem, where water potential is higher. As water leaves the xylem, this creates a lower water potential, thus water flows into the xylem from the roots. The roots will then absorb water from the soil, which has higher water potential.

In the ​ (a)   pathway, water moves from cell to cell via plasmodesmata, while water moves via cell walls in the ​ (b)   pathway.

• symplast
• apoplast

Which of the following is FALSE regarding the xylem vessel?

• It is made of xylem vessel elements joined end to end

• Xylem vessel elements are living cells

• Lignin is deposited in the walls of xylem vessel elements

• Lignin is not deposited around plasmodesmata, forming pits in xylem vessels