BAB 6 Ekologi & Keanekaragaman Hayati | Aliran Energi | Daur Biogeokimia – Kelas 7 Kurikulum Merdeka

Summary

This video discusses ecology and biodiversity for 7th-grade science, focusing on energy flow and biogeochemical cycles. It explains how organisms obtain energy through food chains, emphasizing photosynthesis and energy transfer between trophic levels. Key concepts such as producers, consumers, and decomposers are highlighted. The lesson also covers important natural cycles like the water, carbon, and nitrogen cycles, including processes like evaporation, respiration, and denitrification. Interactive questions encourage engagement, reviewing topics such as the role of decomposers, food webs, and the consequences of population changes in ecosystems.

Takeaways

• 🌱 Energy flows in ecosystems as living organisms require energy to perform life activities, with animals getting energy by consuming plants or other animals.
• 🌞 Plants capture sunlight and convert it into chemical energy via photosynthesis, following the law of energy conservation.
• 🌿 In the food chain, plants serve as producers, while animals like grasshoppers, frogs, snakes, and eagles act as consumers.
• 🔄 Decomposers, such as bacteria and fungi, break down dead organisms into inorganic compounds, cycling nutrients back into the ecosystem.
• 🔥 Only about 10% of energy is transferred from one trophic level to the next in the food chain, with energy being lost as heat or stored in waste.
• 🕸 Multiple food chains interconnect to form a food web, which increases the stability of an ecosystem as complexity grows.
• 💧 The water cycle involves processes like evaporation, transpiration, condensation, and precipitation, ensuring the constant circulation of water in nature.
• 🌬 The carbon and oxygen cycles are driven by processes like photosynthesis and respiration, with carbon dioxide being cycled between organisms and the atmosphere.
• 🦠 The nitrogen cycle includes nitrogen fixation, nitrification, and denitrification, which convert nitrogen between its various forms for use by living organisms.
• ❓ Bacteria and fungi function as decomposers, breaking down dead matter, while carnivores occupy the third and fourth trophic levels in food chains.

Q & A

What is the main source of energy for living organisms?

The main source of energy for living organisms is the sun. Plants convert sunlight into chemical energy through photosynthesis, which then transfers to other organisms through food chains.

How do plants and animals differ in obtaining energy?

Plants obtain energy from sunlight through photosynthesis, while animals acquire energy by consuming plants or other animals.

What does the law of conservation of energy state?

The law of conservation of energy states that energy cannot be created or destroyed, only transformed from one form to another.

What role do plants play in the food chain?

Plants are producers in the food chain because they can produce their own food through photosynthesis, providing energy to other organisms.

What are the different consumer levels in the food chain mentioned in the transcript?

The consumer levels are: grasshoppers as primary consumers (level 1), frogs as secondary consumers (level 2), snakes as tertiary consumers (level 3), and eagles as quaternary consumers (level 4 or apex consumers).

What happens to living organisms after they die?

After death, organisms are decomposed by decomposers like bacteria and fungi, which break them down into inorganic compounds.

Why does only 10% of energy transfer from one trophic level to the next?

Only about 10% of energy transfers because much of the energy is lost as heat or stored in waste, and not all parts of an organism are consumed by the next trophic level.

What is the difference between a food chain and a food web?

A food chain shows a linear sequence of energy transfer between organisms, while a food web is a more complex network of interconnected food chains in an ecosystem.

What are biogeochemical cycles, and can you name three mentioned in the transcript?

Biogeochemical cycles are the continuous movement of chemical elements between living organisms and the environment. The three cycles mentioned are the water cycle, the carbon cycle, and the nitrogen cycle.

How do decomposers obtain their energy?

Decomposers, such as bacteria and fungi, obtain energy by breaking down dead organisms and organic matter into simpler substances.