Click image to open full size
Biology
Plants in Deserts and the Arctic
CAM Photosynthesis, Wax, and Antifreeze
Related Tools
Related Labs
Related Worksheets
Plants survive in deserts and the Arctic by solving the same basic problem: staying alive when conditions make growth difficult. Deserts challenge plants with heat, intense sunlight, scarce water, and dry air. Arctic habitats challenge plants with freezing temperatures, short growing seasons, strong winds, and frozen soil. These extreme environments reveal how natural selection shapes structures and behaviors that conserve energy and protect cells.
Key Facts
- CAM photosynthesis saves water by opening stomata at night and storing CO2 as organic acids.
- Photosynthesis can be summarized as 6CO2 + 6H2O + light energy = C6H12O6 + 6O2.
- Transpiration is water loss from leaves, and it increases when stomata are open in hot, dry air.
- Thick waxy cuticles reduce evaporation by forming a waterproof barrier on plant surfaces.
- Deep tap roots help desert plants reach groundwater, while shallow wide roots capture brief rainfall.
- Arctic plants often grow low to the ground, enter dormancy, and use antifreeze compounds to protect cells.
Vocabulary
- CAM photosynthesis
- A water-saving form of photosynthesis in which plants open stomata at night to take in carbon dioxide.
- Cuticle
- A waxy outer layer on leaves and stems that helps reduce water loss.
- Tap root
- A large main root that grows deep into the soil to reach water and anchor the plant.
- Dormancy
- A low-activity state that helps a plant survive unfavorable seasons until conditions improve.
- Convergent evolution
- The process in which unrelated organisms evolve similar traits because they face similar environmental challenges.
Common Mistakes to Avoid
- Thinking cactus spines are only for defense is wrong because spines are modified leaves that also reduce water loss and shade the plant surface.
- Assuming desert plants grow deep roots only is wrong because many desert plants also use shallow spreading roots to absorb brief rainfall quickly.
- Calling Arctic cushion plants the same as desert succulents is wrong because they may look similarly compact, but their adaptations protect against cold, wind, and short growing seasons rather than heat alone.
- Forgetting that stomata lose water is wrong because gas exchange for photosynthesis also allows water vapor to escape, which is why CAM plants open stomata mostly at night.
Practice Questions
- 1 A cactus opens its stomata for 8 hours at night instead of 12 hours during the day. By what percent is the stomata-open time reduced compared with 12 hours?
- 2 An Arctic plant grows actively for 50 days each year. If it produces 0.18 g of new biomass per day, how much biomass does it produce in one growing season?
- 3 Explain how a cactus and an Arctic cushion plant can show convergent evolution even though one lives in a hot desert and the other lives in a freezing biome.