energy movement in an ecosystem review

describe the order of energy transfer in the food web? (think arrows)

what would happen to the trophic level energy if the mouse were removed.

why is it important to have more biodiversity in an ecosystem?

explain what happens to the amount of energy and number of organisms as you move up the energy pyramid.

how much energy transfers to each trophic level?

which level of organisms has the most available energy?

describe the transfer of energy between a mouse and a snake, if the mouse has 2000 kj of energy?

Question

energy movement in an ecosystem review

describe the order of energy transfer in the food web? (think arrows)

what would happen to the trophic level energy if the mouse were removed.

why is it important to have more biodiversity in an ecosystem?

explain what happens to the amount of energy and number of organisms as you move up the energy pyramid.

how much energy transfers to each trophic level?

which level of organisms has the most available energy?

describe the transfer of energy between a mouse and a snake, if the mouse has 2000 kj of energy?

Accepted Answer

### 1. Describe the order of energy transfer in the food web? (Think arrows)
# Brief Explanations:
In a food web, energy starts from producers (like grass here) which make their own food via photosynthesis. Then, primary consumers (herbivores such as grasshopper, rabbit, mouse) eat the producers. Next, secondary consumers (carnivores or omnivores that eat primary consumers, like lizard, snake) consume the primary consumers. Finally, tertiary consumers (top predators, like hawk) eat the secondary consumers. The arrows show the direction of energy flow, from the organism being eaten to the eater (e.g., Grass → Grasshopper → Lizard → Hawk; Grass → Rabbit → Hawk; Grass → Mouse → Snake → Hawk; Grass → Mouse → Hawk).
# Answer:
Energy transfer order: Producers (Grass) → Primary Consumers (Grasshopper, Rabbit, Mouse) → Secondary Consumers (Lizard, Snake) → Tertiary Consumer (Hawk). Arrows go from prey to predator (e.g., Grass to herbivores, herbivores to their predators).

### 2. What would happen to the trophic level energy if the mouse were removed?
# Brief Explanations:
- **Grass (producer)**: With mouse (a primary consumer) removed, grass has one less herbivore eating it, so grass population may increase, and its energy availability (for other herbivores like rabbit/grasshopper) could rise.
- **Snake (secondary consumer)**: Mouse is a food source for snake. Fewer mice mean less energy input for snakes, so snake population may decrease (due to less food/energy), reducing energy at the secondary consumer level (for snakes).
- **Hawk (tertiary consumer)**: Hawks eat mice and snakes. With fewer mice and potentially fewer snakes, hawks have less energy from these sources. However, hawks also eat rabbits/lizards, so the impact might be partially offset, but overall, energy flow to hawks from the mouse - snake pathway is reduced.
# Answer:
- Grass (producer level): Energy (and population) may increase (fewer mice eating it).
- Snake (secondary consumer level): Energy decreases (less mouse prey), so snake population may drop.
- Hawk (tertiary consumer level): Energy from mouse - snake pathway drops; impact on hawk depends on other prey (rabbit/lizard), but overall, energy flow via mice is reduced.

### 3. Why is it important to have more biodiversity in an ecosystem?
# Brief Explanations:
- **Stability/Resilience**: More species mean more complex food webs. If one species is lost (e.g., a disease kills a herbivore), other species can fill its role (other herbivores eat the same plants), so the ecosystem is more stable and can recover from disturbances (like natural disasters or species loss) better.
- **Resource Utilization**: Different species have different niches (roles). More biodiversity means more efficient use of resources (e.g., different plants use different nutrients, different animals eat different foods at different times/habitats), so the ecosystem can support more life and functions (like nutrient cycling, pollination).
- **Ecosystem Services**: Biodiverse ecosystems provide more services to humans (e.g., more plant species mean more crops, medicines; more animal species help with pest control, pollination) and support natural processes (like soil formation, water purification).
# Answer:
Biodiversity increases ecosystem stability (complex food webs resist change), improves resource use (different niches), and provides more ecosystem services (e.g., food, medicine, pollination, soil health). It also helps ecosystems recover from disturbances (resilience) as alternative species can fill roles if one is lost.

### 4. Explain what happens to the amount of energy and number of organisms as you move up the energy pyramid?
# Brief Explanations:
- **Energy**: In an energy pyramid, only about 10% of energy is transferred from one trophic level to the next (the rest is lost as heat, used for life processes). So as you move up (from producers to primary consumers to secondary, etc.), the amount of available energy **decreases** (e.g., producers have 1000 kJ, primary consumers ~100 kJ, secondary ~10 kJ, tertiary ~1 kJ).
- **Number of Organisms**: Generally, the number of organisms also **decreases** as you move up. Producers (like grass) are most numerous (supporting many herbivores). Primary consumers (herbivores) are fewer than producers. Secondary consumers (carnivores eating herbivores) are fewer than primary consumers, and tertiary consumers (top predators) are the fewest. This is because less energy means fewer organisms can be supported at higher levels (though there are exceptions, like a large predator and many small prey, but the overall trend is decreasing numbers with increasing trophic level).
# Answer:
- Energy: Decreases (only ~10% transferred between levels, rest lost as heat/life processes).
- Number of organisms: Decreases (less energy supports fewer organisms at higher trophic levels, though some exceptions exist, but overall trend is fewer organisms upward).

### 5. How much energy transfers to each trophic level?
# Brief Explanations:
The 10% rule (or 10% energy transfer rule) states that, on average, only about 10% of the energy from one trophic level is transferred to the next trophic level. For example, if producers (trophic level 1) have 1000 kJ of energy, primary consumers (trophic level 2) get about 10% of that, so 100 kJ. Secondary consumers (trophic level 3) get 10% of the primary consumers' energy, so 10 kJ. Tertiary consumers (trophic level 4) get 10% of the secondary consumers' energy, so 1 kJ. The remaining ~90% of energy at each level is used for the organism’s life processes (like respiration, movement) or lost as heat.
# Answer:
On average, about 10% of the energy from one trophic level is transferred to the next trophic level (the 10% rule). The other ~90% is lost as heat or used for life processes.

### 6. Which level of organisms has the most available energy?
# Brief Explanations:
In an energy pyramid, the lowest trophic level (producers, like plants/grass) has the most available energy. This is because energy is lost (as heat, for life processes) at each transfer between trophic levels (only ~10% moves up). So producers, which start the energy flow (via photosynthesis), have the largest energy pool, and each subsequent level (primary consumers, secondary, tertiary) has less energy.
# Answer:
The producer level (e.g., grass in the food web) has the most available energy, as energy is lost at each trophic level transfer (only ~10% moves up).

### 7. Describe the transfer of energy between a mouse and a snake, if the mouse has 2000 kJ of energy?
# Brief Explanations:
Using the 10% energy transfer rule, when a snake (secondary consumer) eats a mouse (primary consumer), the snake will receive about 10% of the mouse’s energy. So calculate 10% of 2000 kJ: $ 2000 \times 0.1 = 200 $ kJ. The remaining 1800 kJ of the mouse’s energy is lost (as heat, used for the mouse’s life processes like moving, respiring, digesting, etc.).
# Explanation:
## Step1: Recall the 10% energy transfer rule.
Energy transferred between trophic levels is ~10% of the lower level's energy.
## Step2: Calculate energy transferred from mouse to snake.
Mouse energy = 2000 kJ. Energy to snake = $ 2000 \times \frac{10}{100} = 200 $ kJ.
# Answer:
When the snake eats the mouse, the snake receives about 10% of the mouse’s energy. So from 2000 kJ in the mouse, the snake gets $ 2000 \times 0.1 = 200 $ kJ. The remaining 1800 kJ is lost (heat, mouse’s life processes).

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QUESTION IMAGE

Question

Explanation:

1. Describe the order of energy transfer in the food web? (Think arrows)

Answer:

2. What would happen to the trophic level energy if the mouse were removed?