Adaptation to environment practice questions.

Outline what is meant by an adaptation in the biological sense.

• A change an individual organism makes during its lifetime in response to the environment
• A heritable feature that increases an organism's fitness in a particular environment
• A behaviour learned from other members of the same species
• A physical injury that alters an organism's appearance

Answer: A heritable feature that increases an organism's fitness in a particular environment

An adaptation is an inherited characteristic that has evolved through natural selection because it improves survival and reproduction in a given environment; non-heritable lifetime changes are acclimatization, not adaptation.

State which term describes the adaptations of a species to the abiotic conditions of the biome it inhabits.

• Convergent evolution
• Abiotic adaptation
• Sexual selection
• Genetic drift

Answer: Abiotic adaptation

Species are adapted to the specific abiotic factors of their biome (e.g. temperature, rainfall, light); these environmental variables act as selection pressures shaping form and function.

Explain why plants in cold, wet coniferous forest biomes often have needle-shaped leaves.

• Needles maximise the surface area available for light capture in low-light conditions
• Needles reduce surface area, limiting water loss and resisting damage from snow and freezing
• Needles allow the plant to store large quantities of water in the leaf
• Needles increase transpiration to cool the plant in freezing temperatures

Answer: Needles reduce surface area, limiting water loss and resisting damage from snow and freezing

The small surface-area-to-volume ratio of needles, combined with a thick cuticle, reduces water loss when soil water is frozen and unavailable, and the shape sheds snow, reducing physical damage.

Determine which adaptation best helps a mammal living in a hot desert environment conserve water.

• Producing large volumes of dilute urine
• Producing highly concentrated urine and small, dry faeces
• Having a thin layer of subcutaneous fat over the whole body
• Sweating continuously throughout the day

Answer: Producing highly concentrated urine and small, dry faeces

Desert mammals such as the kangaroo rat have long loops of Henle that concentrate urine, minimising water loss in excretion; concentrated urine and dry faeces conserve scarce water.

Distinguish the adaptation shown by a cactus stem that is thick, green and photosynthetic.

• The stem stores water and photosynthesises, leaves being spines
• The stem allows rapid transpiration to cool the plant
• The stem anchors the plant deep in sandy soil
• The stem provides a large surface area for gas exchange with the air

Answer: The stem stores water and photosynthesises, leaves being spines

In cacti, leaves are reduced to spines to cut water loss, so the swollen stem stores water and contains chlorophyll to carry out photosynthesis.

A marram grass leaf can roll up when conditions are dry. Explain how this helps the plant.

• It increases the leaf surface exposed to wind, speeding transpiration
• It traps humid air near the stomata, reducing transpiration
• It allows more sunlight to reach the stomata for photosynthesis
• It moves the stomata to the outer surface where evaporation is fastest

Answer: It traps humid air near the stomata, reducing transpiration

Rolling encloses the stomata (which are on the inner surface) in a chamber of humid air, lowering the water-vapour gradient between leaf and outside air, so transpiration is reduced.