Organism and its Environment: Major Abiotic Factors, Practice Problems and FAQs

What would happen if we ran out of water on Earth? What if Earth was drowned in never-ending darkness? Can you imagine life on Earth if the ambient temperature was around 100oC at all times? What would happen if the land around us turned barren and could not support the growth of any plant? Scary questions, right? 

We can hardly imagine life on earth if the major nonliving or abiotic components of our environment, such as water, temperature, soil, light, etc. are not present at optimum conditions. Thus for any organism to survive, both biotic (living) and abiotic (nonliving) factors in its environment play a crucial role. Want to know how the non-living factors play such an important role in our survival? Keep scrolling down!!

Table of Contents:

• Temperature
• Water
• Light
• Soil
• Practice Problems of Organism and its Environment
• FAQs of Organism and its Environment 

Temperature

The most important ecologically relevant environmental factor is the temperature. Temperature hugely affects the survival of living organisms because it controls the enzymatic activity the living body. Thus change in temperature has a direct influence on the metabolic and physiological functions of the body.

The average temperature on land varies seasonally from cold winters to hot summers. It also decreases as we move from the equator towards the poles ( > 500C in tropical regions sub-zero in polar regions).

Some habitats have temperatures beyond 100o C. Example: thermal springs and deep-sea hydrothermal vents.

Different organisms are found in different regions, the temperatures of which are suitable for their survival. 

For example, camels cannot survive at the low temperatures in cold countries of the Arctic region and polar bears cannot stay in grasslands.

Based on the tolerance to temperature, organisms can be classified as eurythermal and stenothermal.

Eurythermal animals 

These are the animals which can tolerate and thrive in a wide range of temperatures. Ex: Sheep, man, cow. You can find these organisms almost all over the world. These can thrive in various regions with varying temperatures.

Stenothermal Animals

These animals can tolerate only a narrow range of temperature, e.g, reptiles, seals etc. These organisms cannot tolerate extreme variations in temperatures other than that of their habitat.

Water

Water is essential for all living beings to survive as it is a major constituent of living systems. Availability of water majorly affects the flora and fauna of a place.

 The vegetation of the desert looks different from that of forests as deserts have xerophytic plants with thick stems and leaves reduced to spines in order to conserve water. The productivity and distribution of plants is also affected by availability of water.

Camels also have adapted to low water availability by minimising water loss. Camels hardly sweat and urinate less frequently to reduce the water loss from the body.

Even organisms which live in water have to face water-related problems as their survival depends on factors such as composition, solute concentration or pH of water. Salt concentration or salinity determines whether an organism can thrive in such water. It is measured in terms of parts of per thousand or ppt. 

Salinity is less than 5 ppt in inland waters, 30-35 ppt in the sea and > 100 in some hypersaline lagoons.

Based on the tolerance to salinity organisms can be euryhaline or stenohaline.

Euryhaline

These are organisms that are tolerant to a wide range of salinity. Example - Atlantic stingray

Stenohaline

These are organisms that are tolerant to a narrow range of salinity. Example - Goldfish

Light

Plants use light energy to produce food through photosynthesis. Thus, light is another important abiotic factor. Since the sun is the source for both light and temperature, the availability of light on land is coupled to temperature. Plants depend on light not only for photosynthesis, but also for flowering.

Not all plants receive the same amounts of sunlight. Many species of small plants growing in the lower strata of forests are adapted to photosynthesise under dim light conditions as the canopy of taller trees overshadows them. These plants have large leaves to capture as much sunlight as possible. 

Animals also indirectly depend on sunlight for energy as plants are directly or indirectly the source of food for all animals. They also use the variations in the intensity of light across the day, during various seasons and the duration of light availability (photoperiod) as signals for collecting food, reproducing or migrating.

The ocean floor hardly receives any light. Organisms living at such depths obtain energy by feeding on dead organic matter received from the zones aabove or synthesise food using chemical energy (chemoautotrophs).

The spectral quality of solar radiation also influences living organisms as the ultraviolet radiations can be fatal to life forms. Moreover, not all the colour components of the visible spectrum are available at different depths of the ocean. 

Blue light reaches the deep ocean. Since red algae absorb blue light, they are found in deep oceans.

Soil

Soil is formed by the weathering of rocks due to physical, biotic and chemical factors. Nature and properties of soil vary in different places due to the variations in climate, weathering factors and the process of soil development and transport. Different types of soil vary in their texture, grain size, aggregation of particles, etc. which in turn determines how much water they can hold or allow to percolate (pass through).

Extent of vegetation in any area depends on:

• Topography 
• Minerals present in the soil
• Soil pH
• Water holding capacity and percolation property of soil

The type of vegetation in turn influences the fauna of the area.

Similarly, in the aquatic environment, the sediment-characteristics of soil often determine the type of animals that can thrive in this habitat. Benthic animals like crabs and clams are found in the areas which are near to the sea.

Practice Problems of Organism and its Environment

1. Read the following statements (I - III) and identify the correct statement(s‌).
2. When the mean annual temperature is plotted against mean annual precipitation in a graph, the tropical forests show the maximum variation in temperature.
3. Light duration and intensity affects plants only and not animals.

III. Temperature can affect the kinetics of enzymes. Thus temperature affects metabolic activity and other physiological functions.

1. 1. I ‌and‌ ‌II ‌
   2.  I ‌and‌ ‌III

• Only III ‌ ‌

1. II and III

Solution: A graph with mean annual temperature against mean annual precipitation, shows that an almost constant temperature is maintained in tropical rainforests. 

Both plants and animals are affected by changes in light intensity and duration.

Temperature can affect the kinetics of enzymes, thereby affecting the metabolic activity and physiological functions of living organisms.

Hence the correct option is c.

1. Select the correct option by matching column I with column II.

1. P - ii, Q - i, R - iii
2. P - iii, Q - i, R - ii
3. P - i, Q - iii, R - ii
4. P - iii, Q - ii, R - i

Solution: Salinity or salt concentration in water is measured in parts per thousand (ppt), that means the number of grams of salts per kilogram of water. The salt concentration is < 5 ppt in inland water, around 30 - 35 ppt in sea water and greater than 100 ppt in hypersaline lagoons.

Hence the correct option is b.

1. Arrange the given events (i - iv) in the process of weathering in the correct order of their occurrence.
2. i) Rainwater that enters the cracks, becomes ice when the temperature drops.
3. ii) Ice or roots of plants can widen the cracks.

iii) Rocks that are exposed to temperature changes will undergo expansion and contraction.

1. iv) Over a period of time the rocks will break and disintegrate into many pieces.

1. iii→i→ii→iv
2. i→ ii→iii→iv
3. i→iii→ii→iv
4. ii→i→iii→iv

Solution: Soil formation starts with the breakdown or dissolving of rocks and minerals, also called as weathering of rocks. Rocks exposed to temperature changes, undergo expansions (with heat), contractions (with cold) and start cracking over time. Rainwater enters these cracks and becomes ice when the temperature drops.Then the ice widens the cracks further. The roots of plants can also cause cracks in the rocks. Slowly, over a period of time, the rocks will break and disintegrate into many pieces. 

Hence the correct option is a.

1. To characterise the habitat of an organism both biotic and abiotic components play an important role which includes: 

1. 1. decomposers and competitors as abiotic components and pathogens and parasites as biotic components.
   2. pathogens and parasites as abiotic components and physico-chemical factors as biotic components .

• physico-chemical factors as abiotic components and pathogens and parasites as biotic components.

1. physico-chemical factors as both biotic and abiotic components.

Solution: Biotic components include any living organism such as plants, fishes, animals, microbes, parasites, predators, pathogens and even competitors. Abiotic components include the physical (temperature, water, light) and chemical (levels of oxygen, nutrients) factors present in the environment of the organisms.

Hence the correct option is c.

FAQs of Organism and its Environment

Quesion 1. What do you mean by an abiotic factor?
Answer. Abiotic components refer to the physical environment of a living organism. It includes temperature, water, light and soil that surround the organism. 

Quesion 2. How organisms are classified based on their tolerance to the temperature?
Answer.Based on the tolerance to temperature, organisms can be classified as eurythermal and stenothermal. 

Eurythermal animals can tolerate and thrive a wide range of temperatures. Example: Sheep, man, cow. 

Stenothermal animals can tolerate only a narrow range of temperatures. Example: reptiles, seals etc. 

Quesion 3. How smaller plants on the forest floor are adapted to photosynthesise?
Answer. Small plants growing near the forest floor are adapted to photosynthesise under dim light conditions as the canopy of taller trees overshadows them. These plants have large leaves to capture as much sunlight as possible. 

Quesion 4. Why is temperature considered a major abiotic factor?
Answer. Temperature can affect the kinetics of enzymes which control all metabolic functions in the body which in turn affect the physiological functions of an organism. Very high temperatures denature or destroy enzymes as they are proteins. This can block metabolic pathways, leading to death of an organism. So temperature is considered as a major abiotic factor.

Other Related Topics Of Biology

• Responses to abiotic factors
• Parasitism and Commensalism
• Predation
• Competition
• Organism and its environment