25 Most VSAQ’s of Ecology and Environment Chapter in Inter 1st Year Zoology (TS/AP)

2 Marks

VSAQ-1 : What is the primardial source of energy for all organisms?

The primary source of energy for all organisms is sunlight. This sunlight is essential for photosynthesis, a process where green plants and certain bacteria convert it into chemical energy in the form of glucose. This energy is then transferred through different trophic levels in the food chain, as organisms consume and are consumed by others. Sunlight plays a critical role in sustaining life and driving ecological processes in the natural world.

VSAQ-2 : What are biological rhythms?

Biological rhythms are regular and recurring behavioral activities in organisms that follow specific time patterns. An example is the circadian rhythm, like the sleep-wake cycle, which repeats every 24 hours. These rhythms play a crucial role in regulating physiological processes, sleep, metabolism, and hormone production in various living beings. They help organisms adapt to environmental changes and maintain internal balance.

VSAQ-3 : What are circadian rhythms?

Circadian rhythms are biological rhythms that occur in a 24-hour time period. These rhythms regulate various behavioral activities and physiological processes in living organisms, such as the sleep-wake cycle. They help organisms adapt to daily environmental changes and maintain internal balance. Circadian rhythms play a crucial role in overall health and well-being, ensuring that essential functions occur at the right time of day.

VSAQ-4 : What is Photoperiodism?

Photoperiodism refers to the response of plants to the relative duration of light and dark periods, which influences their growth, development, and various physiological processes. It primarily affects the timing of flowering in plants. Some plants require specific day lengths (short-day, long-day, or day-neutral) to initiate flowering. Photoperiodism plays a crucial role in regulating plant life cycles, helping them adapt to seasonal changes and optimize their reproductive success.

VSAQ-5 : Mention the advantages of some UV rays to us.

Advantages of UV rays:

  1. Germicidal properties: UV radiation has germicidal properties, effectively killing or inactivating microorganisms present on the body surface of animals, including bacteria, viruses, and fungi. This helps in reducing the risk of infections.
  2. Vitamin D synthesis: UV radiation plays a crucial role in the synthesis of vitamin D in mammals. When exposed to sunlight, the skin’s cholesterol-based compounds are converted into vitamin D, which is essential for bone health, calcium absorption, and immune system function.

VSAQ-6 : What is cyclomorphosis? Explain its importance in Daphnia.

Cyclomorphosis in Daphnia is a rapid, reversible change in morphology in response to predators. It helps them adapt and avoid predation, increasing their chances of survival and reproduction in changing environments.

VSAQ-7 : Define commensalism. Give one example.

  1. Commensalism is an interspecific interaction where one species benefits, and the other is unaffected.
  2. Example: Clownfish and sea anemones. Clownfish gain protection, while sea anemones remain unaffected.

VSAQ-8 : Define mutualism. Give one example.

  1. Mutualism is an interspecific interaction where both species benefit.
  2. Example: Lichens, which consist of a mutualistic association between a fungus and photosynthetic algae or cyanobacteria.

VSAQ-9 : What is meant by osmotrophic nutrition?

Osmotrophic nutrition is the absorption of pre-digested food material through the body surface. This process involves nutrient diffusion across the cell membrane into the organism’s body.

VSAQ-10 : What is an ecosystem?

An ecosystem is a biological community of interacting organisms (biotic factors) and non-living physical elements (abiotic factors) in a specific environment. It includes plants, animals, microorganisms, air, water, soil, and more. Ecosystems involve complex interactions and energy/nutrient cycles.

VSAQ-11 : Distinguish between lotic and lentic habitats.

Lotic Habitats:

  1. Flowing water (rivers, streams).
  2. One-directional flow.
  3. Well-oxygenated.
  4. Species adapted to flowing water.

Lentic Habitats:

  1. Still or slow-moving water (ponds, lakes).
  2. Stationary or gentle flow.
  3. Variable oxygen levels.
  4. Species adapted to calm or stagnant water.

VSAQ-12 : Distinguish the terms photoaxis and photokinesis.


  1. Directed movement of an organism in response to the intensity or direction of light.
  2. Typically involves a directional response, such as moving toward or away from a light source.
  3. Examples include plants bending toward light (phototropism) or single-celled organisms moving toward light (positive phototaxis).


  1. Non-directed, random movement of an organism in response to light.
  2. Does not involve a specific orientation or direction in response to light.
  3. Examples include the random movements of microorganisms when exposed to light without a defined pattern or direction.

VSAQ-13 : What is camouflage? Give its significance.

Camouflage is a defensive adaptation in which an organism’s appearance, coloration, or behavior allows it to blend into its surroundings, making it less visible to predators or prey. The significance of camouflage is to enhance an organism’s survival by reducing the risk of detection, predation, or capture. It helps organisms avoid being seen by predators, making it more challenging for them to locate or capture potential prey. Camouflage can also aid in ambush hunting for predators, making it easier to approach prey without being noticed. Overall, camouflage improves an organism’s chances of survival and successful reproduction in its natural habitat.

VSAQ-14 : Which air pollutants are chiefly responsible for acid rains?

The air pollutants chiefly responsible for acid rain are sulfur dioxide (SO2) and nitrogen oxides (NOx). When these pollutants are released into the atmosphere from sources such as burning fossil fuels and industrial processes, they can undergo chemical reactions with other atmospheric components and form sulfuric acid (H2SO4) and nitric acid (HNO3). These acids then combine with water vapor in the atmosphere and fall to the ground as acid rain, which can have harmful environmental effects on aquatic ecosystems, forests, and buildings.

VSAQ-15 : What is BOD?

Biochemical Oxygen Demand (BOD) is a measure of the amount of dissolved oxygen consumed by microorganisms while breaking down organic matter in water under aerobic conditions and at a specific temperature. It is used as an indicator of water quality and the level of organic pollution in water bodies. High BOD levels indicate a high concentration of organic pollutants, which can lead to reduced oxygen levels in the water and negatively impact aquatic life. Monitoring BOD helps assess the health of aquatic ecosystems and the effectiveness of wastewater treatment processes.

VSAQ-16 : What is Biological magnification?

Biological magnification, also known as biomagnification, is the process by which certain toxic substances, such as pesticides or heavy metals, increase in concentration as they move up the food chain. As organisms consume contaminated food, the toxins accumulate in their tissues and become more concentrated in higher trophic levels. This phenomenon can have serious implications for higher-level consumers, like predatory birds or mammals, as they end up with significantly higher concentrations of the harmful substances. It highlights the potential dangers of environmental pollutants impacting higher-level organisms in the food chain.

VSAQ-17 : Why are incinerators used in hospitals?

Incinerators are used in hospitals for the disposal of hazardous medical waste. Hospitals generate various types of waste, including infectious materials, sharps (needles, scalpels), chemicals, and other potentially harmful substances. Incineration is an effective method to safely and completely destroy these hazardous wastes, reducing the risk of spreading infections and preventing environmental contamination. Incineration ensures proper treatment and disposal of medical waste, protecting both public health and the environment.

VSAQ-18 : Define parasitism. Give one example?

Parasitism is a symbiotic relationship between two organisms where one organism benefits at the expense of the other organism, the host. The parasite derives nourishment and shelter from the host while causing harm to the host.

An example of parasitism is the relationship between clownfish and sea anemones. Clownfish live among the tentacles of sea anemones, which provide protection for the clownfish from predators. In return, the clownfish offer no apparent benefits to the sea anemones. The clownfish benefit from shelter and protection, while the sea anemones are not affected by their presence.

VSAQ-19 : What is optimum temperature?

Optimum temperature refers to the specific temperature at which an organism’s metabolic activities are most efficient and occur at the highest rate. For humans, the optimum temperature is around 98.4°F (37°C), which is the normal body temperature. At this temperature, various physiological processes in the body function optimally, supporting overall health and homeostasis. Any significant deviation from this optimum temperature can lead to health issues and discomfort.

VSAQ-20 : Distinguish between photoperiod and critical photoperiod.

  1. Photoperiod refers to the duration of light and darkness experienced by organisms in a 24-hour cycle. It is the time interval between sunrise and sunset.
  2. Critical photoperiod, on the other hand, is the specific day length that triggers certain seasonal events in organisms. It is the minimum or maximum amount of light exposure required to induce particular physiological responses, such as flowering in plants or migration in animals, based on their adaptation to different environmental conditions.

VSAQ-21 : What is PAR?

PAR stands for Photosynthetically Active Radiation. It refers to the part of the solar radiation that falls within the wavelength range of 400 to 700 nanometers, which is essential for photosynthesis in plants. However, plants can utilize only 2-10% of the total PAR available for photosynthesis. Additionally, PAR constitutes less than 50% of the total incident solar radiation received on Earth.

VSAQ-22 : What is the percentage of PAR, in the incident solar radiation.

The percentage of Photosynthetically Active Radiation (PAR) in the incident solar radiation available on Earth is less than 50%. PAR represents the portion of solar radiation with wavelengths between 400 to 700 nanometers, which is crucial for photosynthesis in plants. The rest of the incident solar radiation consists of wavelengths beyond this range, which are not utilized by plants for photosynthesis.

VSAQ-23 : Distinguish between neuston and nekton.

  1. Neuston: Surface-dwelling organisms in the surface film of water bodies.
  2. Nekton: Aquatic organisms capable of active, independent swimming throughout the water column.

VSAQ-24 : What is Gause’s principle? When does it applicable?

Gause’s principle, also known as competitive exclusion principle, states that two species with similar ecological niches cannot coexist indefinitely in the same habitat. When they compete for the same limited resources, one species will eventually outcompete and displace the other. This principle applies when resources are limited and helps explain competitive interactions in ecosystems. It is often studied in laboratory experiments.

VSAQ-25 : What is predation? Give an example.

Predation is a key ecological interaction where one species, the predator, hunts, kills, and consumes another species, the prey. A classic example is lions preying on deer, helping regulate populations and maintain ecosystem balance.