Two species of a plant genus ipomea share a common niche and reproductive pattern but are still unable to hybridize because they have structurally different flowers. what kind of reproductive isolation is observed in these two species?

Mechanical isolation

Explanation:

Mechanical mechanism of reproductive isolation operates as one of the prezygotic mechanisms. In this process, the incompatibility of the structure of the reproductive organs between populations does not allow them to interbreed.

In the given example, two species of genus Ipomea can not interbreed irrespective of their presence in the same habitat and same reproductive behavior. These two species produce flowers which are not compatible with each other and do not allow these two species to interbreed. Since structural incompatibility is operative here, it is a mechanical mechanism of prezygotic isolation.  

the menstrual cycle – higher tier. negative feedback mechanisms affect the production of hormones in the menstrual cycle. oestrogen also stimulates the release of lh (luteinising hormone) from the pituitary gland, which in turn controls the production of progesterone.

the answers are a and c