12th Class Biology Chapter 25 Quiz with Answers

“12th Class Biology Chapter 25 Quiz: Ecosystem” introduces students to the intricate relationships between organisms and their environments, focusing on how these interactions shape ecosystems. An ecosystem includes all living organisms in a particular area, interacting with each other and their physical environment. This chapter covers the components of ecosystems, energy flow, nutrient cycling, and the importance of maintaining ecological balance. To aid in your understanding, explore our MDCAT Quiz and free flashcards, designed to help reinforce your knowledge and prepare for exams.

Energy Flow in Ecosystems

Energy flows through an ecosystem in a one-way direction, originating from the sun. The sun is the primary source of energy for most ecosystems. The energy flow can be understood through the concept of food chains and food webs.

Food Chain: A linear sequence of organisms, where each organism serves as food for the next trophic level. In a grassland ecosystem, the grass is eaten by herbivores like rabbits that are in turn eaten by carnivores like foxes.

Food Web: A more complex, interwoven system of food chains that illustrates how energy and nutrients flow in an ecosystem. In a food web, organisms may be part of multiple food chains.
The flow of energy is represented through trophic levels:

Nutrient Cycling

Nutrient cycling is the process by which essential elements like carbon, nitrogen, and phosphorus are recycled in ecosystems. These nutrients are constantly being used by living organisms and released back into the environment through processes like decomposition.

MDCAT Quiz: Ecosystem

Test your knowledge of ecosystems with our MDCAT Quiz. The quiz covers major topics including energy flow, trophic levels, nutrient cycles, and ecological balance. This quiz will help in reinforcing your understanding and will ensure that you are well prepared for any exam questions.

• Test Name: 12th Class Biology Chapter 25 Quiz
• Type: Quiz Test
• Total Questions: 30
• Total Marks: 30
• Time: 30 minutes

Note: Answer of the questions will change randomly each time you start the test, once you are finished, click the View Results button.

Free Flashcards for Ecosystem

Review key material from this unit with our FREE ecosystem dynamics flashcards. These focus on key issues such as food chains, the flow of energy, biogeochemical cycles, and human impact on the ecosystem. Flashcards are a great way of doing quick review and enhancing the ability to remember key terms.

Ecosystems are central to the functioning of the Earth’s biosphere. Through an understanding of the balance between biotic and abiotic elements, along with the flow of energy and nutrients, you can fathom the complexity of nature and the need for its preservation. Use MDCAT Quiz and flashcards to strengthen your knowledge and score well in your exams.

Which of the following is a human activity that can disrupt ecosystems?

Deforestation

What is the term for the process by which water moves through the soil and into groundwater?

Infiltration

Which of the following is an example of a natural ecosystem service?

Pollination

What is the term for the study of the interactions between organisms and their environment?

Ecology

What is the term for the area where an organism lives and obtains its resources?

Habitat

Which of the following is a characteristic of a stable ecosystem?

High biodiversity

What is the term for the process by which organisms regulate their internal environment to maintain stability?

Homeostasis

Which of the following is a greenhouse gas that contributes to global warming?

Carbon dioxide

What is the term for the process by which excess nutrients in water lead to increased plant growth and oxygen depletion?

Eutrophication

What is the term for the process by which pollutants accumulate in the tissues of organisms as they move up the food chain?

Biomagnification

Which of the following is a measure of the total amount of dissolved salts in water?

Salinity

Which of the following is a limiting factor for plant growth in most ecosystems?

Nitrogen

Which of the following is a primary source of phosphorus for ecosystems?

Rocks

What is the term for the process by which nitrogen compounds are converted back into nitrogen gas by bacteria?

Denitrification

What is the term for the process by which bacteria convert ammonia into nitrites and then into nitrates?

Nitrification

What is the term for the process by which nitrogen gas is converted into ammonia by bacteria?

Nitrogen fixation

Which of the following is an example of an abiotic factor in an ecosystem?

Temperature

Which of the following is an example of a biotic factor in an ecosystem?

Plants

What is the term for the role of an organism within its ecosystem?

Niche

What is the term for the number of different species in a given area?

Biodiversity

What is the term for the gradual process of change and replacement of the types of species in a community?

Succession

Which biome is characterized by grasses, scattered trees, and a lack of precipitation?

Grassland

Which biome is characterized by dense forests with high levels of precipitation?

Rainforest

Which biome is characterized by low temperatures, little precipitation, and permafrost?

Tundra

What is the term for the process by which carbon dioxide is released into the atmosphere by burning fossil fuels?

Combustion

What is the term for the process by which water moves from the atmosphere to the Earth's surface?

Precipitation

What is the term for the process by which water evaporates from the leaves of plants?

Transpiration

What is the term for the total mass of living organisms in a given area?

Biomass

What is the trophic level of an organism that feeds on secondary consumers?

Tertiary consumer

What is the trophic level of an organism that feeds on primary consumers?

Secondary consumer

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