NEET BIOLOGY

Detailed explanation-1: -In cacti, gray thorns are dominant to red thorns. If, for some reason, no one know why, you feel the need to determine the genotype of a gray thorned cactus. What kind of cactus would you cross it with? There is no way to determine the genotype of the original gray thorned cactus.

Detailed explanation-2: -By shading the cactus, these spines also help prevent the cactus from losing water through evaporation. So all in all, spines are adaptations that protect and help cacti hide from animals that may want to eat them. They also provide shade for the plant, which keeps them cooler and limits water loss.

Detailed explanation-3: -Over time, those leaves evolved into the spiky spines we see on cactuses today because they help the plants survive in hot, dry environments. “They can be a defense mechanism to discourage herbivores-animals that eat plants-from eating the cactus. But, also, spines create shade!” explains Kimberlie McCue.

Detailed explanation-4: -Stems in cactus are comparatively thicker than other plants, hence it is able to store water in stems – specifically in collapsible water-storage cells. The stems can also expand considerably to store more water. They are green and perform photosynthesis.

Detailed explanation-5: -Spines are also modified leaves. In cacti, spines are wholly transformed leaves that protect the plant from herbivores, radiate heat from the stem during the day, and collect and drip condensed water vapour during the cooler night.