Questions and Answers
What is the primary source of energy for plants?
Which method is used to measure the dry mass of an organism?
What percentage of dry mass is generally considered to be carbon in an organism?
What role do producers play in an ecosystem?
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What happens to some of the glucose produced during photosynthesis?
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Which of the following best defines biomass in the context of an organism?
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In an ecosystem, what are abiotic conditions?
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How can biomass be typically expressed in scientific measurements?
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What is net primary productivity (NPP)?
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How is the gross primary productivity (GPP) calculated?
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In a calorimetry experiment, what does the temperature change of the water indicate?
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What is the correct formula for calculating the net production of consumers (N)?
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Which of the following statements about a niche is true?
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Approximately what percentage of gross primary production is typically lost as respiratory heat?
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What does secondary production refer to in an ecosystem?
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Which unit is typically used to express primary productivity?
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What happens during the process of primary production?
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Which of the following defines the term 'respiratory loss' (R)?
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Study Notes
Energy Sources in Ecosystems
- Plants obtain energy from sunlight, while animals derive energy by consuming plants or other animals.
- Energy transfers involve losses, but calculations can quantify transferred energy using specific equations.
Measuring Biomass
- Biomass is measured in terms of carbon mass or dry mass of tissues per unit area (e.g., kg m^-2).
- Dry mass is the organism's mass after water has been removed, ensuring accurate biomass assessment.
- To determine dry mass, a sample is dried (often in a low-temperature oven) and weighed until mass stabilizes.
- Approximately 50% of dry mass is carbon; scaling up results provides total biomass for an area.
Ecosystem Overview
- An ecosystem consists of living organisms and abiotic factors in a specific area.
- Producers create their own food through photosynthesis, using sunlight and carbon dioxide to make glucose and other sugars.
- Some sugars are utilized for respiration to provide energy and aid growth; others contribute to biomass.
Energy Transfer in Trophic Levels
- Energy flows through an ecosystem when organisms consume others: producers are eaten by primary consumers, followed by secondary consumers.
- Gross Primary Production (GPP) is the total chemical energy converted by plants.
- About 50% of GPP is lost as heat during respiration (Respiratory Loss, R).
- Remaining energy is termed Net Primary Production (NPP), calculated as: NPP = GPP - R.
Calorimetry
- Chemical energy in biomass can be estimated by burning the biomass in a calorimeter.
- The heat released is measured to calculate energy content, expressed in joules (J) or kilojoules (kJ).
Primary Productivity Calculations
- Calculate Net Primary Productivity (NPP) for grass as: 20,000 kJ m^-2 yr^-1 (GPP) - 8,000 kJ m^-2 yr^-1 (R) = 12,000 kJ m^-2 yr^-1.
- For tundra, GPP equals 2,800 kJ m^-2 yr^-1 (NPP) + 1,250 kJ m^-2 yr^-1 (R) = 4,050 kJ m^-2 yr^-1.
Consumer Energy Analysis
- Net production of consumers (N) can be determined by the formula: N = I - (F + R), where:
- I = chemical energy from ingested food
- F = chemical energy lost in waste
- R = respiratory losses
- Net production of consumers, also known as secondary production, is termed secondary productivity when expressed as a rate.
Primary Production Rate
- Primary production is often expressed as a rate: total chemical energy in an area over time (e.g., kJ ha^-1 yr^-1 or kJ m^-2 yr^-1).
Understanding Niche
- A niche represents a species’ role within its habitat, encompassing its dietary habits and activity patterns.
- Niche includes biotic interactions (e.g., feeding relationships) and abiotic factors (e.g., temperature tolerance).
- Each species has a unique niche; two species may occupy similar niches but differ in specific behaviors or diets.
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Description
Explore the mechanisms of energy transfer in ecosystems through this quiz. Learn about sources of energy, biomass measurement techniques, and the interplay between living organisms and their environment. Perfect for students studying environmental science or biology.
