Practice - Part 1: Energy for Life – Photosynthesis and Cellular Respiration
Practice Questions
Test your understanding with targeted questions
What are the two main types of organisms based on how they obtain energy?
- Answer: Autotrophs and Heterotrophs.
- Hint: Think about "self-feeders" versus "other-feeders."
💡 Hint: Think about "self-feeders" versus "other-feeders."
What is the primary purpose of ATP in a cell?
- Answer: To provide usable energy for cellular activities.
- Hint: It's often called the cell's "energy currency."
💡 Hint: It's often called the cell's "energy currency."
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Interactive Quizzes
Quick quizzes to reinforce your learning
What is the primary energy source for autotrophs?
- Type: mcq
- Options: A) Sunlight, B) Glucose, C) ATP, D) Carbon Dioxide
- Correct Answer: A
- Explanation: Autotrophs, like plants, use sunlight to produce food through photosynthesis.
- Hint: Consider how plants get their energy initially.
💡 Hint: Consider how plants get their energy initially.
Do heterotrophs produce their own energy?
- Type: boolean
- Options: True, False
- Correct Answer: False
- Explanation: Heterotrophs do not produce their own food; they obtain energy by consuming other organisms.
- Hint: Think about who needs to eat to get energy.
💡 Hint: Think about who needs to eat to get energy.
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Challenge Problems
Push your limits with advanced challenges
Design an experiment to compare the rate of anaerobic respiration in yeast at two different temperatures (e.g., 25°C and 40°C). Outline your hypothesis, independent variable, dependent variable, at least three controlled variables, and a simple procedure for collecting quantitative data.
- Solution:
- Hypothesis: If yeast is at 40°C, its rate of anaerobic respiration ( production) will be faster than at 25°C, up to an optimal point, because enzymes are more active at warmer temperatures, but too high will denature.
- Independent Variable: Temperature (25°C vs. 40°C).
- Dependent Variable: Rate of production (e.g., volume of gas collected in a gas syringe).
- Controlled Variables: Volume of yeast suspension, concentration of glucose solution, type of yeast, duration of experiment.
- Procedure: Prepare two identical sealed containers with yeast and glucose. Place one in a 25°C water bath and the other in 40°C. Measure the volume of gas collected in a syringe over 30 minutes at 5-minute intervals. Compare the rates.
- Hint: Think about controlling all other factors to isolate the effect of temperature.
💡 Hint: Think about controlling all other factors to isolate the effect of temperature.
A forest ecosystem relies heavily on its trees for energy. If a severe drought occurs, explain in detail how this abiotic factor (drought) would initially impact the energy transformation processes within the trees, then how it might affect the overall energy flow and balance of the entire forest system.
- Solution: Drought reduces water availability, a key input for photosynthesis. Trees close stomata to prevent water loss, which also stops uptake. This drastically slows photosynthesis, reducing glucose production. With less glucose, trees have less energy for growth and maintenance. This reduces the primary productivity of the forest. Herbivores then have less food, causing their populations to drop, which ripples up to carnivores. The entire ecosystem's energy flow is restricted, potentially leading to a collapse of food webs.
- Hint: Trace the impact from the initial biological process (photosynthesis) through the food chain.
💡 Hint: Trace the impact from the initial biological process (photosynthesis) through the food chain.
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