ZOO507 Final Term Past Papers

M.IMRAN

Q1. Aestivation (2 marks)

Aestivation or summer sleep is a period of inactivity and low metabolic rate in animals in response to high temperature and dry season. Aestivation is common in many invertebrates, reptiles, and amphibians. Aestivation is a kind of adaptation in some animals that helps them to survive in extended periods of drying. The animal usually enters a burrow as its environment begins to dry. It generally does not eat or drink and emerges again after moisture returns. The Australian burrowing frog, Cyclorana alboguttatus, in its burrow and waterretaining skin.

Q2. Exploitation (2 marks)

The diversity of interactions between herbivores and plants, between predators and prey, and between parasites, parasitoids, pathogens, and hosts can be grouped under the heading of exploitation--interactions between species that enhance the fitness of one individual at the expense of another.

Q3. Global warming (2 marks)

The average temperature of earth surface is increasing day by day due to increase in concentration of greenhouse gases in the atmosphere. Human activities are main cause of it. The earth is gradually heating up due to rise in temperature. This phenomenon is called Global warming. It is causing serious problems to the health of plants and animals and also the surrounding environment.

Q4. Counter shading (3 marks)

Counter shading is a type of color pattern in animals in which there is a dark pigmentation on the upper surface of body and light pigmentation on the lower surface of body. Counter shading helps an animal to blend in with its surrounding environment. Counter shading is a kind of camouflage common in frog and toad eggs. These eggs are darkly pigmented on top and lightly pigmented on the bottom. When a bird or other predator views the eggs from above, the dark of the top side hides the eggs from detection against the darkness below. On the other hand, when fish view the eggs from below, the light undersurface blends with the bright air-water interface. Penguins are another example that exhibit phenomenon of counter shading.

Q5. Solid waste (3 marks)

Solid wastes refer to everything that goes out in trash. Municipal solid wastes are wastes from homes, offices, stores, schools, hospitals, etc., that are collected and disposed by the municipality.

Solid waste is usually disposed of in landfills. Landfills take up space and, if not properly contained, can leach toxins into the soil and poison groundwater.

In countries with limited space, solid waste is burned at high temperatures that creates very hazardous ash, and pollutes the air with toxic chemicals. Hospitals generate hazardous wastes that contain disinfectants and other harmful chemicals, and also pathogenic micro-organisms. Such wastes also require careful treatment and disposal.

The use of incinerators is crucial to disposal of hospital waste.

Irreparable computers and other electronic goods are known as electronic wastes (Ewastes).

E-wastes are buried in landfills or incinerated.

Recycling involves manual participation thus exposing workers to toxic substances present in ewastes

Solid waste management

All waste that we generate can be categorised into three types,

1. Recyclable
2. Bio-degradable,
3. Non-biodegradable.

Q6. Overexploitation (3 marks)

Overexploitation of resources (or using resources at an unsustainable rate) is a critical problem in conservation. The overexploitation or nonsustainable use of wildlife is closely linked and plays an increasing role in the loss of biodiversity Overharvesting, nonsustainable use, and the illegal trade in some species are threatening not only their continued survival but also that of ecosystems and the livelihoods of communities and local economics that depend upon them.

Unsustainable hunting, fishing, logging, or gathering of wild populations leads to their commercial, ecological or global extinction.

Overexploitation can be divided into two major categories:

o Direct exploitation o Indirect exploitation

Direct exploitation ranges from commercial activities such as logging operations or trade in endangered species to subsistence hunting.

Indirect exploitation:

Indirect exploitation encompasses the unintentional mortality of non target species such as fish or turtles killed as by-catch in fishery operations. Both endanger species around the world.

Q7. Primary succession wth exampl (5 marks)

The process by which a new community is propagated or initiated in an area where previously no life forms exist is termed as primary succession. Primary succession takes thousands of years to develop by the gradual accumulation of nutrients. Communities begin to establish in areas which are devoid of life. The first community to become established in an area is called the pioneer community. The organisms that develop this pioneer community are called pioneers. Examples are lichens and mosses whose seeds or spores are distributed by the wind and carried by animals. Death, decay, and additional nutrients add to the community. Over thousands of years nutrients accumulate, and the characteristics of the ecosystem changes.

Seral stage

Each successional stage is called a seral stage.

Sere

The entire successional sequence is termed as a sere.

Biomass increases, nutrients are conserved more efficiently, and productivity declines in the course of succession.

Climax community

The relatively stable and uniform community developed by the pioneers through different successional stages is named as climax community. It is a final and mature stage of any community. Primary succession on a sand dune. Beach grass is the first species to become established. It stabilizes the dune so that shrubs, and eventually trees, can grow.

Q8. Ozone layer depletion and its effects (5 marks)

Ozone gas is continuously formed by the action of UV rays on molecular oxygen, and also degraded into molecular oxygen in the stratosphere. There should be a balance between production and degradation of ozone in the stratosphere. This balance is disrupted due to ozone degradation by Chlorofluorocarbons (CFCs). CFCs are released by refrigerants. CFCs discharged in the lower part of atmosphere move upward and reach into stratosphere. In stratosphere, UV rays act on them releasing chlorine (Cl) atoms. Cl degrades Ozone releasing molecular oxygen. So CFCs have permanent and continuing affects on Ozone levels. This increase in release of Chlorofluorocarbons (CFCs) has created a large area of thinned ozone layer in Antarctic region, commonly called as the ozone hole.

Effects of Ozone depletion

• Skin cancer
• Snow-blindness (inflammation of cornea by UV-rays.
• Cataract

. Low crop

production

Q9. Resource depletion & biodiversity (5 marks)

Humans are either directly or indirectly exploiting about 40% of the earth’s net primary production. It involves converting natural areas to agricultural uses, frequently substituting less efficient crop plants for native species. The main threats to biological diversity arise from habitat destruction by expanding human populations. Habitat loss displaces thousands of native plants and animals. Some of the most important threatened natural areas include, o Tropical rain forests, o Coastal wetlands, o Coral reefs. Of these, tropical rain forests have probably received the most attention. Tropical rain forests cover only 7% of the earth’s land surface, but they contain more than 50% of the world’s species. Tropical rain forests are being destroyed rapidly, mostly for agricultural production. About 76,000 km2 (an area larger than Costa Rica) is being cleared each year. Clearing of tropical rain forests achieves little, because the thin, nutrient-poor soils of tropical rain forests are exhausted within two years.