Science 6 ILEARN Practice #1

What is something introduced to a system that can be positive (increase changes in the system) or negative (reduce change in the system)?

The purpose is to help restore a system (such as an animal or ecosystem) to homeostasis (having everything they need met).

• Homeostasis

• Feedback mechanism

• Tomato

• Decomposer

A musk thistle plant was moved into a new environment. The musk thistles grew very well in their new home. Other plants in the area began to die because the musk thistles were taking all the nutrients from the soil.

A scientist discovered the problem and decided to bring in weevils. Weevils eat musk thistles. The weevils ate the musk thistles and greatly reduced their numbers. Some of the plants native to the area began to grow again.

Which statement from the story describes a feedback mechanism that is keeping a population within certain limits?

• The musk thistles grew very well in their new home.

• A scientist discovered the problem and decided to bring in weevils.

• The weevils ate the musk thistles and greatly reduced their numbers.

• Some of the plants native to the area began to grow again.

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What is the process where plants collect energy from the Sun, and absorb water and carbon dioxide to create food (a type of sugar--glucose) to survive and some leftover oxygen (for us to breathe)?

• Photosynthesis

• Homeostasis

• Biodiversity

• Consumers

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Choose the correct words or phrases to fit into the blanks to complete the sentence.

1. Sugar
2. Oxygen
3. Stay warm
4. Solar energy
5. Dispose of waste
6. Grow and reproduce
7. Make food for consumers

Plants use the process of photosynthesis to make A:_____________ so that they can B:__________________________.

• A: 1 B: 7

• A: 1 B: 6

• A: 4 B: 5

• A: 2 B: 3

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Which of the following is a type of species that has been brought by humans into an ecosystem they don't belong in. Only then, they don't fit in, harm the ecosystem, take away food, shelter, or other needs from native organisms, etc.

• Endangered species

• Extinct species

• Invasive species

• Miniscule species

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In 1990, zebra mussels, an invasive species which are not native to North America, had been found in all the Great Lakes. Zebra mussels eat algae.

Which of these will MOST LIKELY happen as the population of zebra mussels in the Great Lakes increases?

• Native algae eaters will increase

• Native algae eaters will decrease

• Native algae eaters and predators of zebra mussels will increase

• Native algae eaters and predators of zebra mussels will decrease

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Homeostasis

• allows for a wildly fluctuating internal environment

• is impossible in vertebrates

• is the maintenance of a relatively stable internal environment and often incorporates a form of feedback regulation

• is the maintenance of a relatively stable external environment and often incorporates a form of feedback regulation

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Biologists study the effect of different temperatures on breathing in goldfish. The number of times the fish open their gills determines how many breaths the fish take.

The biologists place goldfish in three different fish tanks. The tanks are at different temperatures. They count the number of breaths taken in five minutes. Their data is given in Table 1.

Why are the breathing rates of the fish different in each tank?

• Warm water has less oxygen, so they have to breathe more often to get the needed oxygen.

• Warm water speed up a fish's metabolism, making it need more oxygen (which it gets by breathing faster).

• Fish alter their breathing rate to adapt to changes in their environment, helping them maintain homeostasis.

• Fish breathe faster in colder water to avoid freezing.

The arrows in a food chain or web represents what?

• They point to the organism that is being eaten.

• It shows how sunlight flows within an ecosystem.

• They show what direction the energy is flowing between organisms.

• They represent how water is transferred within a habitat.

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Choose which of the following is the best food web for this tundra ecosystem.

• 
• 
• 

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