IB Bio 9.1

The image is a cross section through an Ammophila leaf, which grows on coastal sand dunes.

What feature suggests that Ammophila is a xerophyte?

• A. The leaf surface area is increased.

• B. The rolled leaf reduces the upper epidermis area.

• C. The rolled leaf protects the lower epidermis from the wind.

• D. The lower epidermis can transpire more easily.

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

• A.

• B.

• C.

• D.

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

A. Active translocation of mineral ions in roots

B. Active transport of organic compounds into sieve tubes

C. Raised hydrostatic pressure gradients

D. Evaporation of water from mesophyll cell walls

• A.

• B.

• C.

• D.

The graph shows the percentage of stomata that are open in two different species of plants over a 24-hour period.

What does this graph show about plants X and Y?

• A. Plant X absorbs most carbon dioxide at night.

• B. Plant Y is adapted to desert conditions.

• C. Plant X photosynthesises most at midday.

• D. Plant Y only respires during the day.

The image shows part of a section through the stem of a non-woody plant. Where does transport of sucrose occur?

• A.

• B.

• C.

• D.

The apparatus in the diagram was used to assess the effects of factors on transpiration rates.

Which factor would be a controlled variable in an experiment designed to assess the effects of temperature on transpiration rate?

• A. The opening and closing of stomata

• B. The opening and closing of stomata

• C. The height of the water in the reservoir

• D. The evaporation of water from the leaves

Excessive irrigation can cause increased salinity in the soil. What effect does this have on water transport in the plant roots?

• A. Decreases movement of water from soil into the root

• B. Absorption of water with a higher solute concentration

• C. Increases movement of water from soil into the root

• D. Absorption of water with a lower solute concentration

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

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

• B. By loading organic compounds in the phloem of the roots

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

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

What is transported in xylem tissue?

• A. Sucrose from leaves to fruits

• B. Starch from leaves to storage organs

• C. Water from roots to leaves

• D. Salts from soil to roots

Which abiotic factors affect transpiration in plants?

• A. temperature, humidity and wind

• B. pH, temperature and salinity

• C. light, pH and humidity

• D. humidity, temperature and salinity