2nd Year NotesBiology class 12th

2nd year Chapter 26 Some Major Ecosystem

2nd year Chapter 26 Some Major Ecosystem Question and Answer

Short And Simple Question and Answer

Q.1 How is ecological balance disturbed in a eutrophic lake?

Ans. Eutrophic lakes experience excessive nutrient input, often from human activities like agricultural runoff or sewage discharge. This leads to an overgrowth of algae, disrupting the ecological balance as most trophic levels in the food web are affected, and the lake becomes dominated by bacteria and blue-green algae.

Q.2 Differentiate between weather and climate?

Ans. Weather refers to short-term fluctuations in temperature, humidity, cloud cover, wind, and precipitation over periods of hours or days. Climate, on the other hand, represents the overall patterns of weather in a region over an extended period, typically years or decades.

Q.3 How can the productivity of an ecosystem be measured?

Ans. Ecosystem productivity can be measured by examining the consumption of carbon dioxide (CO2) and the release of oxygen during photosynthesis. In aquatic ecosystems, productivity is primarily determined by factors like light availability and nutrient concentrations.

Q.4 Give the role of water in the lithospheric ecosystem?

Ans. Water plays a critical role in lithospheric ecosystems by providing essential moisture to support plant life. While soil contains abundant nutrients, water is often limited and unevenly distributed both spatially and temporally, influencing the types of organisms that can thrive.

Q.5 Give the impact of temperature on terrestrial ecosystems?

Ans. Temperature has a significant impact on terrestrial ecosystems. Favorable temperatures are not uniformly distributed across the Earth’s surface in terms of both location and time. Some areas, such as polar regions, have average temperatures below freezing, while temperate zones may only experience favorable temperatures during certain seasons.

Q.6 Differentiate between arctic and alpine tundra?

Ans. Arctic tundra is found at high latitudes, typically in polar regions like the Arctic Circle, whereas alpine tundra is located at high altitudes on mountains. Both are characterized by cold, harsh conditions and limited vegetation.

Q.7 Give the flora of the tundra?

Ans. The tundra is known for its low-stature vegetation, including small perennial flowers, dwarf willows, and often large lichens like reindeer moss.

Q.8 Give examples of animal life in the tundra?

Ans. The tundra is home to various bird species, including ducks and geese. Many of these birds migrate over long distances. Insect life, like mosquitoes and other insects, also thrives near standing water in the tundra.

Q.9 What are the human impacts on the tundra?

Ans. Human activities, such as oil drilling, pipeline construction, mining, and the establishment of military bases, have had adverse effects on the tundra. These impacts can persist for centuries, leading to habitat disruption and environmental damage.

Q.10 What is the effect of scum on life in a lake?

Ans. Scum on the surface of a lake, often caused by algal blooms, can negatively impact life in the lake. These blooms can reduce oxygen levels in the water, harming aquatic organisms. Additionally, scum can interfere with recreational activities and water quality.

Q.11 What is scum and how is it formed?

Ans. Scum is formed when added nutrients promote the growth of phytoplanktons like blue-green algae, which accumulate on the lake’s surface.

Q.12 What types of plants are found in the littoral zone of a lake?

Ans. In the littoral zone of a lake, you’ll find a diverse range of plants, including water lilies, submerged vascular plants, and algae. These plants thrive at varying depths within the littoral zone.

Q.13 What are planktons?

Ans. Planktons are microscopic floating organisms.

Q.14 How do phytoplanktons differ from zooplanktons?

Ans. Phytoplanktons are photosynthetic planktons, while zooplanktons are non-photosynthetic planktons.

Q.15 What distinguishes marine ecosystems from freshwater ecosystems?

Ans. Marine ecosystems, such as saltwater oceans and seas, cover about 71% of the Earth’s surface, while freshwater ecosystems represent less than 1% of the planet’s surface.

Q.16 What is the impact of temperature on aquatic ecosystems?

Ans. Water changes temperature more slowly than air, resulting in moderate and stable temperatures in aquatic ecosystems, which are conducive to supporting life.

Q.17 How much light energy can water absorb in aquatic systems?

Ans. Water can absorb a significant amount of light energy, vital for sustaining life on Earth. However, the intensity of light decreases rapidly with depth, leaving little light for photosynthesis at depths of 600 feet or more.

Q.18 What is the productivity of grassland ecosystems?

Ans. In temperate grasslands, the rate of primary production is approximately 700-1500 g/m² annually, while sub-humid tropical grasslands can have over 4000 g/m² of annual production.

Q.19 What are the human impacts on grassland ecosystems?

Ans. Human activities in natural grasslands, such as crop production and livestock management, often lead to overgrazing, reducing herbage cover, causing soil erosion, and even contributing to desertification.

Q.20 What defines a desert?

Ans. A desert is an ecosystem characterized by arid conditions with an annual rainfall of less than 30 cm (10 inches).

Q.21 What are Thal, Cholistan, and Thar?

Ans. Thal, Cholistan, and Thar are regions known for their distinct landscapes and ecosystems, including deserts and grasslands.

Q.22 What is desertification?

Ans. Desertification is the process of deserts spreading into once-green areas due to human activities, which reduce various biomes, leading to the expansion of deserts.

Q.23 What is a grassland ecosystem?

Ans. A grassland ecosystem is characterized by grassy landscapes and an annual rainfall ranging from 250 to 750 mm.

Q.24 How do prairies and savannas differ?

Ans. Prairies are grasslands without woody trees, while savannas are grasslands with scattered woody trees.

Q.25 How are grass layers formed in the grassland ecosystem?

Ans. In a grassland ecosystem, tall grasses like Andropogon and Panicum form the first layer, while mid-high grasses like Stipa, Sporobolus, and Oryzopsis form the second layer.

Q.26 What distinguishes alpine and boreal coniferous forests?

Ans. Alpine forests are located at high altitudes, whereas boreal coniferous forests are situated at high latitudes.

Q.27 What animals inhabit alpine and boreal coniferous forests?

Ans. Large mammals found in these ecosystems include bison, wolves, black bears, deer, and Marco Polo sheep. Small animals include the small Kashmir flying squirrel, snowshoe hare, wolverine, and crossbills.

Q.28 What is the human impact on alpine and boreal forests?

Ans. While many coniferous forests remain undisturbed due to their remote and severe climates, they are still a major source of timber for construction. As a result, a significant number of forests have been cleared worldwide.

Q.29 Where are temperate deciduous forests located in the world?

Ans. Originally, temperate deciduous forests covered regions in India, Southeast Asia, Europe, China, Australia, Japan, North America, and South America.

Q.30 What adaptations do plants in temperate deciduous forests have for conserving water?

Ans. Plants in temperate deciduous forests shed their leaves during dry seasons to minimize water loss. They delay the formation of new leaves if there’s no rain on schedule during a drought.

Q.31 How does life exist in the profundal zone?

Ans. The profundal zone lacks sufficient light for photosynthesis. Instead, life in this zone mainly relies on detritus as a source of nourishment. Detritus from the littoral and limnetic zones, carried by incoming sediment, serves as a food source for decomposers and detritus feeders in the profundal zone.

Q.32 What is eutrophication of a lake?

Ans: Eutrophication of a lake refers to the increased rate of biological activity in a nutrient-rich lake or pond.

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