110 practice questions covering How Nature Works in Harmony, organised into 0 topics.
110 questions include a written explanation.
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Sample questions
Q1
hard
If all the decomposers in a forest suddenly vanished, the most likely long-term result would be that
Anothing would change, since decomposers feed only on waste
Bdead leaves and remains would pile up and the soil would grow poorer in nutrients
Cplants would grow faster because nothing would compete with them
Devery herbivore in the forest would die within a day
Show answer and explanation
Correct answer: B - dead leaves and remains would pile up and the soil would grow poorer in nutrients
Decomposers break down dead matter and hand its nutrients back to the soil, so without them the remains would collect while the soil slowly lost its supply of nutrients. Plants would suffer rather than benefit from that loss. The change would be large, not nothing, but it would build up over months, not kill herbivores in a day.
Q2
easy
Pollination is important for our food supply because
Apollination kills the pests that attack a crop
Bpollination adds nutrients to the soil of a field
Cmany crops form fruits and seeds only after their flowers are pollinated
Dpollination supplies water to the growing crop
Show answer and explanation
Correct answer: C - many crops form fruits and seeds only after their flowers are pollinated
Pollen must reach a flower before fruits and seeds can develop, and fruits and seeds are what we harvest from many crops. Watering and feeding the crop are quite separate matters handled by rain, irrigation and manure. Pollination does nothing to control pests.
Q3
medium
Assertion (A): A pond is an example of an ecosystem. Reason (R): Water plants in a pond make their own food using sunlight.
ABoth A and R are true, and R is the correct explanation of A
BBoth A and R are true, but R is not the correct explanation of A
CA is true, but R is false
DA is false, but R is true
Show answer and explanation
Correct answer: B - Both A and R are true, but R is not the correct explanation of A
Both statements are true. However, a pond counts as an ecosystem because its living things and its water, mud, air and sunlight all interact as one unit, not because of what its plants happen to eat. Food-making by water plants is one activity inside the pond, so R does not explain A.
Q4
medium
Plastic bags thrown into open drains in a town commonly lead to
Amore dissolved oxygen in the drain water
Ba faster flow of water through the drains
Ccleaner drains that need less maintenance
Dblocked drains and water logging during heavy rain
Show answer and explanation
Correct answer: D - blocked drains and water logging during heavy rain
Bags collect at bends and gratings and trap other rubbish, so the drain chokes and rainwater backs up into the streets. Adding waste to a drain cannot clean it or speed the flow. Rotting waste in blocked water reduces the oxygen in it rather than adding to it.
Q5
easy
Green plants are called producers because
Athey make their own food using sunlight
Bthey release oxygen only at night
Cthey take in ready-made food from the soil
Dthey are rooted in one place
Show answer and explanation
Correct answer: A - they make their own food using sunlight
Producers are organisms that build their own food, and green plants do this using sunlight, water and carbon dioxide. They absorb water and minerals from the soil but not ready-made food. Oxygen is released during the day when food is being made, and staying rooted has nothing to do with the name.
Q6
easy
Non-biodegradable waste is waste that
Abreaks down completely within a few days
Bis always in liquid form
Ccannot be broken down by decomposers
Dis always dangerous to touch
Show answer and explanation
Correct answer: C - cannot be broken down by decomposers
The word describes waste that decomposers are unable to break down, so it remains in the soil or water for years. Waste that disappears in a few days is biodegradable instead. Such waste may be solid or liquid, and much of it, such as a glass bottle, is quite safe to handle.
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