Question

How are cactus adapted to survive in deserts?

Answer 1

Cacti have evolved extensive shallow roots, lack of leaves, green stems for water storage and photosynthesis, spines to deter animals, and a unique night-time carbon fixation process for optimal water conservation and survival in desert environments.

Step-by-step explanation:

Adaptations of Cacti to Desert Conditions

Cacti have developed remarkable adaptations to survive in the arid desert environment. To conserve water, some species like the saguaro cactus have extensive shallow root systems that absorb moisture quickly from rare rainfalls. They lack traditional leaves, decreasing water loss through transpiration. Instead, the saguaro's green stem handles photosynthesis and stores water. This allows cacti to retain water efficiently within their barrel-shaped bodies. Additionally, their spines serve to deter animals from consuming their stored water.

Furthermore, cacti have evolved specialized photosynthetic processes for extreme conditions. They use a carbon fixation/storage process at night when temperatures are cooler, allowing them to open their stomata with minimal water loss. During the day, they use the CO₂ captured at night for photosynthesis, keeping their stomata closed to conserve water even further.

Desert travelers' observations that cactus juice is sweeter during the day could stem from the fact that stored sugars from photosynthesis are at their peak due to the closure of stomata, which limits water loss and CO₂ uptake during the hotter daylight hours.

Answer 2

1. They have evolved their leaves into spikes for minimum water loss through transpiration.

2. They have a waxy layer for minimum water loss.

3. They have thick walls for minimum water loss.

4. They can take water from atmosphere.

5. They change the photo energy from Sun into an intermediate stage and store it, so that they can make food even in night.