Adaptation: Question 7
Which BEST explains why a population of a certain species of cactus developed longer spines over time?
Select one:

An animal migrated into the area, and it could only eat short-spined cacti.

A reptile moved into the area, and it could only eat cacti with either very short or very long spines.

A bird migrated into the area, and it could only eat long-spined cactus.

A mammal migrated into the area, and it could only eat cacti with medium-length spines.

dna is made up of six smaller molecules -- a five carbon sugar called deoxyribose, a phosphate molecule and four different nitrogenous bases (adenine, thymine, cytosine and guanine).

organisms that lack symmetry are called asymmetrical and belong to phylum porifera/sponges.

organisms with specialized stinging cells belong to phylum cnidaria. stinging cells are called cnidoblast cells.

cnidarians show two morphological forms : polyp (sessile) and medusa (mobile)

filter feeding is observed in porifera members.  

alternation of generation is observed in coelenterata or cnidaria. there is alternation of asexual polyp form and sexual medusoid form. it is also referred as metagenesis.

climate change and pollution

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