Biogeography & Ecosystems

Statement 1 is correct: Volcanic action releases carbon dioxide trapped within the Earth's crust and mantle. Statement 2 is correct: Respiration releases carbon dioxide as a byproduct of cellular respiration in living organisms. Statement 3 is incorrect: Photosynthesis removes carbon dioxide from the atmosphere. Plants and other photosynthetic organisms use carbon dioxide during photosynthesis to create organic molecules. Statement 4 is correct: The decay of organic matter releases carbon dioxide as decomposers break down dead plants and animals. This process returns carbon stored in organic matter back to the atmosphere as carbon dioxide.

There are concerns about the use of brominated flame retardants (BFRs) for two main reasons: Statement 1 is correct: They are highly resistant to degradation. BFRs break down very slowly in the environment, meaning they can persist for a long time. This can lead to them accumulating in the environment over time. Statement 2 is correct: BFRs can accumulate in the bodies of humans and animals (Bioaccumulation). This happens because they are fat-soluble, meaning they are stored in fatty tissues.

Statement 1 is correct: At such high temperatures, tipping points like widespread forest dieback and permafrost thaw would release vast amounts of stored carbon, causing the land to emit more carbon than it absorbs. Statement 2 is correct: Scientific consensus indicates that even at 2°C of warming, over 99% of coral reefs are expected to be lost. A 3°C rise would ensure their catastrophic and widespread collapse. Statement 3 is incorrect: The word "All" is an extreme overstatement. While many wetlands would be severely damaged or lost, it is not scientifically plausible that every single one would disappear permanently. Statement 4 is incorrect: The term "anywhere" is an exaggeration. While global food production would be devastated, cultivation would not become impossible everywhere; it might shift to new, higher-latitude regions.

In organisms called lichens, a chlorophyll-containing partner, which is an algae, and a fungus live together. Fungus provides shelter, water, and minerals to the algae. In return, the algae provides food which it prepares by photosynthesis.

Statement 1 is correct: This is a major threat. Dams fragment the river habitat, hinder migration patterns, and can disrupt prey availability for the dolphins. Statement 2 is incorrect: While competition might exist, it's not a cause of decline. A healthy river ecosystem can support both dolphins and crocodiles. Statement 3 is correct: This is a significant threat, as dolphins can get caught in fishing gear and drown. Statement 4 is correct: Runoff from agricultural lands can pollute rivers with pesticides and fertilizers. These pollutants can harm the dolphins' health and prey species. Thus 1,3, and 4 are the causes of the decline in the Ganga River Dolphins.

Continental drift: The movement of continents over millions of years has led to changes in the distribution of landmasses, altering habitats and creating opportunities for species to migrate, adapt, and diversify. It has influenced speciation events by creating barriers to gene flow and promoting allopatric speciation. Glacial cycles: Fluctuations in global climate associated with glacial-interglacial cycles have had profound effects on ecosystems and species distributions. Periods of glaciation have resulted in the expansion and contraction of ice sheets, leading to changes in sea levels, habitats, and the distribution of flora and fauna. These environmental changes have driven evolutionary processes such as adaptation, migration, and extinction. Therefore, both continental drift and glacial cycles have played significant roles in shaping the evolution of organisms.

Statement 1 is correct: Oak trees are a common sight in the temperate forests of the Himalayas, particularly at mid-altitudes. Statement 2 is correct: Rhododendrons are a diverse group of flowering shrubs that thrive in the cool, moist conditions of the Himalayas. They are known for their vibrant blooms and are a characteristic feature of the Himalayan landscape. Statement 3 is incorrect: Sandalwood is not typically found in the Himalayas. It prefers drier climates and is more commonly associated with tropical regions like southern India.

Hibernation is a state of decreased physiological activity and lowered body temperature that certain animals, such as bats and bears, undergo during the winter months to conserve energy and survive periods of limited food availability. Statement 1 is correct: Bats, especially those living in temperate regions, often enter a state of hibernation during the colder months when their food sources (insects) are scarce. Statement 2 is correct: Bears, including the brown bear, black bear, and polar bear, are well-known hibernators. Statement 3 is correct: Many rodent species, including groundhogs and chipmunks, are true hibernators. Thus, all three statements are correct.

During photosynthesis, solar energy is converted into chemical energy and stored in sugar molecule bonds. This chemical bond energy is potential (stored) energy.

Out of the three organisms listed, only 2. Nostoc is commonly used as a biofertilizer. Agaricus: This is a type of mushroom and not typically used as a biofertilizer. Nostoc: This is a filamentous, nitrogen-fixing cyanobacterium. Cyanobacteria, also known as blue-green algae, are one of the main groups of organisms used in biofertilizers due to their ability to fix atmospheric nitrogen and make it available to plants. Spirogyra: This is a green alga and not generally used as a biofertilizer.