Worksheet: Decomposition

In this worksheet, we will practice explaining the effect of temperature, water content and oxygen on the rate at which organic material decomposes.

Q1:

What biological molecules are used by decomposers to break down organic material?

  • ALipids
  • BDNA
  • CCarbohydrates
  • DmRNA
  • EEnzymes

Q2:

The picture shows a selection of food products placed in airtight packaging. How does this help slow down the rate of decomposition?

A variety of sausages and ham in air-72ppl
  • AThe microorganisms that carry out decomposition require a good supply of carbon dioxide, which has been removed.
  • BThe microorganisms that carry out decomposition require a good supply of oxygen, which has been removed.
  • CThe microorganisms that carry out decomposition require access to natural light, which has been removed.
  • DThe microorganisms that carry out decomposition need to regulate their own body temperature, which is harder in airtight packaging.

Q3:

Which of the following best explains why warmer temperatures allow faster decomposition?

  • AA warmer temperature decreases the heat energy of the decomposers, so it reduces the rate of enzyme-controlled reactions.
  • BA warmer temperature allows the decomposers to better regulate their body temperature, so they can act faster.
  • CA warmer temperature provides more heat energy to increase the rate of enzyme-controlled reactions.
  • DA warmer temperature increases the moisture content of the soil, which speeds up decomposition.

Q4:

What biological process do decomposers carry out that requires oxygen to be available?

  • AMitosis
  • BAerobic respiration
  • CTranscription
  • DPhotosynthesis
  • EExcretion

Q5:

Which of the following conditions would not increase the rate of decomposition?

  • AA moist environment
  • BA warm environment
  • CA good availability of oxygen
  • DA cold environment

Q6:

Some food waste was left to decompose in a dark, warm corner of a lab. After 12 days, the food waste decreased in mass by 8 grams. Calculate the rate of decay, in grams per day, giving your answer to two decimal places.

  • A1.50 grams per day
  • B0.67 grams per day
  • C0.96 grams per day
  • D0.7 grams per day

Q7:

The graph shows the mass of an apple, in grams, compared to the days it was left in a compost bin. Which of the following conclusions is correct?

  • AThe rate of decomposition in the first 15 days is slower than the rate in the last 15 days.
  • BThe rate of decomposition in the first 15 days is faster than the rate in the last 15 days.
  • CThere is no correlation between the time (days) and the rate of decomposition.

Q8:

The graph shows how a mass of plant material changes as it is left to decompose. Calculate the rate of decomposition between days 0 and 10, in percent per day.

  • A5%/day
  • B1%/day
  • C10%/day
  • D0.1%/day

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