Samacheer Class 9 Science - Environmental Science

• (a) Biological factors
• (b) Abiotic factors
• (c) Biotic factors
• (d) Physical factors

Answer:
(c) Biotic factors

• (a) Evaporation
• (b) Condensation
• (c) Sublimation
• (d) Infiltration

Answer:
(c) Sublimation

• (a) Photosynthesis
• (b) Assimilation
• (c) Respiration
• (d) Decomposition

Answer:
(a) Photosynthesis

• (a) Carbon monoxide
• (b) Sulphur dioxide
• (c) Nitrogen dioxide
• (d) Carbon dioxide

Answer:
(d) Carbon dioxide

Answer: False. Correct Statement: Nitrogen is not a greenhouse gas. The major greenhouse gases responsible for global warming and climate change are carbon dioxide, methane, nitrous oxide, and water vapor. While nitrogen comprises about 78 percent of the atmosphere, it does not trap heat like greenhouse gases do. Carbon dioxide and methane are the most important anthropogenic greenhouse gases contributing significantly to the greenhouse effect and climate change.

Answer: False. Correct Statement: Poorly developed roots are an adaptation of hydrophytes, not mesophytes. Hydrophytes are plants that live in aquatic or waterlogged environments where soil oxygen is limited. They have poorly developed root systems because they do not need extensive roots to absorb water, as water is abundantly available in their habitat. Mesophytes are plants adapted to moderate moisture conditions and typically have well-developed root systems to absorb water from soil. Xerophytes, adapted to dry conditions, have deep and extensive root systems to search for water in the soil.

True. Bats are indeed the only flying mammals. While many other animals can glide or move through the air, bats are the only mammals that possess true wings and the ability to sustain powered flight. Their wings are formed by a membrane of skin stretched between elongated finger bones and their body, which allows them to maneuver with great precision in the air. This unique adaptation makes bats exceptional among all mammalian species.

False. Earthworms do not use echoes for navigation. The correct statement is that bats use echolocation, which is a sophisticated biological sonar system. Bats emit ultrasonic sounds that are beyond the range of human hearing, and these sound waves bounce off objects in their environment. By listening to the returning echoes, bats can determine the location, size, shape, and texture of objects around them, allowing them to navigate and hunt effectively in complete darkness. Earthworms, being soil-dwelling organisms, rely on other sensory mechanisms such as sensitivity to vibrations and chemical cues for navigation and finding food.

False. Aestivation does not help organisms overcome cold conditions. The correct statement is that aestivation is a state of dormancy or reduced metabolic activity that helps organisms survive hot and dry conditions. During aestivation, animals enter a sleep-like state where their body processes slow down significantly, reducing their need for water and food. This adaptation is particularly important for organisms living in deserts and other arid environments where temperatures are extremely high and water is scarce. Hibernation, by contrast, is the dormancy state that helps organisms survive cold winter conditions.

Xerophytes are plants that grow in dry habitats where water is scarce. These plants have evolved special adaptations to survive in arid and semi-arid environments. One of their most important adaptations is having deep roots that extend far into the soil to reach water sources that are located deep underground. These deep root systems allow xerophytes to absorb water from deeper soil layers where moisture is more readily available, even when the surface soil is completely dry. This adaptation enables xerophytes to maintain their water supply during prolonged periods of drought and extreme heat.

Answer:

• Streamlined body helps movement through soil.
• Setae provide grip and anchorage in burrows.

Answer:

• Farm ponds require enough land and capital.
• Small landholdings may not have space for ponds.
• Some fields have unsuitable topography, porous soil or steep slopes.
• Low rainfall or insufficient catchment area may not fill the pond.
• Land ownership, legal or land-use issues may also prevent construction.

Answer:

(i) Biotic Factors

Living components:

• plants
• animals
• microorganisms

(ii) Abiotic Factors

Non-living components:

• air
• water
• sunlight
• temperature
• soil

Adaptation is a special feature, characteristic, or trait that helps an organism survive and reproduce successfully in its habitat. Adaptations can be structural, such as the thick fur of polar bears or the long neck of giraffes, or they can be behavioral, such as migration patterns or hunting techniques. Adaptations develop over many generations through the process of natural selection, where organisms with beneficial traits are more likely to survive and pass those traits to their offspring. These features allow organisms to obtain food, escape predators, withstand environmental conditions, and interact effectively with other members of their species.

Answer:

• Excess water and submergence.
• Low oxygen availability around roots and submerged parts.
• Mechanical damage by water currents.
• Need for buoyancy and support.
• Changing water levels or salinity.

Answer:

• Water is precious natural resource
• Essential for all living organisms
• Freshwater availability is limited

Answer:

• Repair leaking taps
• Use low-flow taps
• Reuse water
• Use recycled water for gardens

Answer:

• Agriculture
• Public parks
• Construction
• Cooling in industries
• Toilet flushing

IUCN stands for International Union for Conservation of Nature. It is a global organization dedicated to the conservation of nature and the sustainable use of natural resources. The vision of IUCN is to create a just world that values and conserves nature. IUCN works to protect biodiversity, promote sustainable development, and address environmental challenges through research, policy advocacy, and conservation projects. The organization brings together governments, non-governmental organizations, scientists, and local communities to develop and implement conservation strategies that benefit both nature and people.

Answer:

• Deep root system
• Thick waxy cuticle
• Leaves reduced to spines
• Water-storing tissues
• Short life cycle during rainy season

Examples:

• Opuntia
• Aloe vera
• Acacia

Answer:

• Live in caves
• Nocturnal habit
• Use echolocation
• Undergo hibernation
• Wings adapted for flight