Topic 9 HL Biology Plant Biology

Which process is most responsible for movement of water from roots to leaves of a plant on a hot sunny day?

• Active translocation of mineral ions in roots

• Active transport of organic compounds into sieve tubes

• Raised hydrostatic pressure gradients

• Evaporation of water from mesophyll cell walls

In the micrograph of a plant stem, which letter indicates the xylem?

• A

• B

• C

• D

A fungicide dissolved in water was applied to the soil in which a rose plant was growing. It later appeared in the leaves. How did the fungicide reach the leaves?

• Movement up a water potential gradient

• Transpiration pull in xylem

• Translocation in phloem

• Facilitated diffusion

How do water molecules enter root cells?

• Transpiration

• Tension

• Capillary action

• Osmosis

Cobalt chloride paper is blue when dry but turns pink with water. Blue cobalt chloride paper was fastened to the upper and lower surfaces of a plant leaf. After 20 minutes, many small pink dots were observed on the paper on the lower surface, and a few pink dots were seen on the upper surface. What conclusions can be drawn?

I. There are more stomata on the lower surface than on the upper surface.

II. Stomata on the upper surface are blocked by the waxy cuticle.

III. More transpiration occurs through the lower surface than through the upper surface.

• I and II only

• I and III only

• II and III only

• I, II and III

Which structure found in eukaryotes has a single membrane?

• Nucleus

• Lysosome

• Chloroplast

• Mitochondrion

Which process and cause are responsible for water uptake by the roots?

• A

• B

• C

• D

Which is the most efficient way for some desert plants to conserve water?

• By having no leaves, so water evaporates from the green stem with less surface

• By loading organic compounds in the phloem of the roots

• By accumulating salt within their tissues, so water is retained by osmosis

• By growing long hair on their surface, so air moisture is absorbed at night

The image shows part of a section through the stem of a non-woody plant. Which feature distinguishes the transport of materials in the tissue labelled I from that in the tissue labelled II?

• In II, active transport is used.

• In II, products of photosynthesis are transported.

• In I, movement of materials is the result of transpiration.

• In I, there is a higher solute concentration.

19M.1.HL.TZ2.40 [1 mark]

What could be used in a technique for measuring flow rates in phloem?

I. Potometers

II. Aphid stylets

III. ¹⁴CO₂

• I and II only

• I and III only

• II only

• II and III only