The wind makes pollination possible for gymnosperms. In gymnosperms ovaries are absent and the gametophytes of these plants are present on cones rather than flowers. Unlike angiosperms that get pollinated with animal interference, wind plays a crucial role in gymnosperm pollination.
Answer: (B) Pre-zygotic; post-zygotic.
Explanation:
Prezygotic isolation occurs before fertilization of eggs. It occurs between the two sex gametes and deter sexual reproduction between different species.
However, individuals are considered to be diverge on the phylogeny tree and different species, when they cannot reproduce.
Mechanisms of prezygotic isolation include habitat isolation, gamete isolation, mechanical isolation, behavioral isolation, and mating seasons.
Whereas, postzygotic isolation prevents the formation of fertile offspring. This phenomenon leads to production of an hybrid offspring from different species and this is a form of speciation in nature.
Mechanisms of postzygotic isolation include hybrid inviability, hybrid breakdown, and hybrid sterility.
Answer:
The carrying ability of an ecosystem is the overall growth rate of a biological species that can be supported by that area, provided the available food, habitat, water, and other resources.
Explanation:
A pond populated briefly by ten turtles, for such, would be sustainable for the species' population.
Cancer cells are the cells that divide rapidly than any other cells in the body. The drugs used in chemotherapy work on rapidly dividing cancer cells. Some cells of our body apart from cancer cells also divide rapidly along with the cancer cells such as the cells that line the stomach and the digestive tract. Chemotherapy drugs cannot differentiate the cancer cells and the normal cells so these drugs also attack the normal cells which divide rapidly along with the cancer cells. The drugs also attack the cells that are present in the roots of the hair. So, this results in the hair loss. Hair loss does not occur immediately after the chemotherapy treatment instead it starts after few treatments. The degree of the hair loss after chemotherapy depends on the drug type and process. So when the chemotherapy drugs are used it results in the hair loss and nausea.
Therefore, when chemotherapy drugs attack normal cells including the roots of the hair instead of cancer cells that divide rapidly along with the cancer cells it results in the hair loss and nausea.
