Plant Adaptations

Question 1

Xerophytes

Answer 1

• Xerophytes are plants which are adapted to environments with very little water availability.
• This can b plants in both hot and cold deserts.
• Examples are cacti and marram grass.

Question 2

Ways of conserving water

Answer 2

• Thick waxy cuticle and thick leaves reduce water loss as it increases diffusion pathway.
• Sunken stomata reduces air movement and keeps humid air which reduces water potential gradient. Most stomata found at the bottom of leaf as it is colder.
• Reduced no. of stomata.
• Spines on leaves create microclimate of humid air and reduces water pot. gradient.

Question 3

Cacti

Answer 3

• Thick waxy cuticle.
• Spines instead of leaves.
• Close their stomata at the hottest time of day to reduce transpiration.

Question 4

Marram grass

Answer 4

• Sunken stomata
• Layer of hair on epidermis which reduces water pot. gradient as it traps warm air.
• In hot/windy conditions they roll their leaves which traps warm air thus reducing water pot. gradient.
• Thick waxy cuticle waterproof.

Question 5

Hydrophytes

Answer 5

• Plants that live in water and need adaptations to cope with growing in water or permanently saturated soil.
• Examples are water lilies.
• It is important that surface water plants have leaves that float so they can photosynthesise.
• Water logging can occur where air spaces in plants are filled w/ water instead of air.

Question 6

Adaptations of hydrophytes

Answer 6

• Very thin or no waxy cuticle and they don’t need to conserve water.
• Many always open stomata on upper surface to max. gaseous exchange. Guard cells are inactive.
• White flat leaves so leaves can spread across surface and capture max light,
• Air sacs in leaf to allow them to float.

Question 7

Water lily

Answer 7

• Have Aerenchyma tissue which is specialised parenchyma tissue with air spaces that allow leaves to float and can act as a store for oxygen for respiration.
• Stomata on upper epidermis.