Biology Test 364

Pyramid of numbers in a forest ecosystem is spindle shaped. In a forest ecosystem, number of producers is lesser but supports a greater number of herbivores. Which in turn support a fewer number of carnivores. This results in spindle shaped structure of pyramid of numbers.

The correct answer is: Option A: A, C, D and E only

A. Tropical latitudes have remained relatively undisturbed for millions of years, hence more time was available for species diversification. This is a major factor contributing to species richness in the tropics. The absence of major geological events like glaciation has allowed for continuous evolution and diversification.

C. More solar energy is available in tropics. This leads to higher productivity, supporting a greater number of species.

D. Constant environments promote niche specialization. Stable conditions allow species to specialize and adapt to specific niches, leading to greater diversity.

E. Tropical environments are constant and predictable. This allows species to evolve specific adaptations to their environment, leading to further specialization and diversification.

Statement B is incorrect: Tropical environments are less seasonal, not more seasonal.

The primitive atmosphere of earth was reducing atmosphere with little or no oxygen but was rich in water vapour, carbon monoxide, carbon dioxide, nitrogen and hydrogen. Thus, oxygen was not present in primitive atmosphere. The high temperature, UV light and lightening provided energy for chemical reactions between hydrogen and free oxygen, nitrogen and carbon to form, ammonia, methane and cyanides. Owing to the high temperature of earth, water was present in form of superheated steam and ammonia, methane and cyanides were present in gaseous form.

Therefore, the correct answer is option C.

Pioneer community is the first community to inhabit an area while the last stable community of an ecological succession is climax community. Climax community has the maximum diversity and niche specialisation.

Hibernation is an adaptation which has evolved in certain group of animals to conserve energy by slowing down metabolism and keeping their body temperature low in winters.

Bats and bears are well known for hibernating. Some of the hibernating animals includes fish, frogs and turtles, snakes, bees, hedgehogs which have no way to keep warm during winter.

Hibernation helps animal to survive when there is inadequate food supply. Before entering into hibernating state an animal stores enough fat to consume it during hibernation.

So, the correct option is 'Hibernation'.

Predators help control prey populations, often preventing prey from reaching excessively high densities. This is a natural ecological balance.

The given pyramid represents pyramid of biomass in an aquatic ecosystem. In this pyramid, biomass of phytoplanktons, i.e., producers (represented by A) is smaller than that of zooplanktons, i.e., primary consumers (represented by B). Phytoplanktons support zooplanktons as the latter feed upon them.

Thyrocalcitonin also known as calcitonin is a polypeptide hormone secreted by the parafollicular or C cells of the thyroid gland. It lowers the levels of calcium and phosphate in the blood and promotes the formation of bone. Thus, the correct answer is option A.

Neurilemma (also known as neurolemma, sheath of Schwann, or Schwann's sheath) is the outermost nucleated cytoplasmic layer of Schwann cells (also called neurilemmocytes) that surrounds the axon of the neuron. It forms the outermost layer of the nerve fiber in the peripheral nervous system.

In an open ocean, the large numbers of phytoplankton quickly complete their life cycles and sets of new population or crops of phytoplankton are formed every few hours or days. Thus, the cumulative energy contents that these generation after generation of phytoplankton trap in course of a year is certainly much more than trapped by only a few generations of herbivorous fishes in the corresponding time and space. The energy content trapped by the carnivores living on the herbivorous fishes is the leat.