The rate is how quickly something takes place. The rate of a reaction is a measure of how much change occurs per unit of time.

The point at which a reaction is complete, often indicated by a change in colour of an indicator.

A precise, measurable and testable statement based on observations about how something works.

The part of an enzyme where the substrate binds.

A permanent change in the shape of an enzyme which stops it from working.

The effect of temperature on the rate of decomposition by an enzyme: data analysis and evaluation

Biology

Components of an ecosystem

Measuring the size and distribution of populations of organisms

Estimating population size using quadrats: practical

Estimating population size and distribution using transects: practical

Competition and adaptations in ecosystems

The role of microorganisms in decomposition

Factors affecting the rate of decomposition

The effect of temperature on the rate of decomposition by an enzyme: practical

Material cycles: the carbon cycle

Material cycles: the water cycle

Pupils will learn about biomass transfer including calculating the efficiency of transfers between trophic levels. They will learn about human impacts on the environment, food security and biotechnology to help maintain biodiversity and achieve food security.

Pupils learned about interdependence within ecosystems and how plants and animals are adapted to their environment. Pupils undertook ecological sampling to estimate population sizes and looked at the impact of humans on biodiversity.

This unit explores ecosystem organisation, biotic and abiotic factors, material cycling, and the role of decomposers. It covers methods for identifying species and measuring their distribution. Emphasis is on selecting appropriate techniques, accurate measurements, sampling, and fieldwork practices.

Living organisms and their environments

In an experiment to determine the effect of temperature on the rate of decomposition by an enzyme, it takes 5 seconds for the indicator to reach the end point. What is the rate of the reaction?

indicator (used to measure the end point)

the product (decreases pH of the solution)

A range of equipment and chemicals are used in the experiment to determine the effect of temperature on the rate of decomposition by an enzyme. Match the words with their function in the experiment. 

At which of the following points are enzymes being denatured?

The active sites of the enzymes are changing as it becomes denatured.

The number of collisions between enzymes & substrate are most frequent.

There are fewer collisions taking place between the enzyme and substrate.

Point b in the graph is known as the enzyme's optimum temperature. Which of the following statements explains what is happening at point 'b'?

What is the name of the part of the enzyme that the substrate needs to collide with for a reaction to take place?

The fridge door prevents oxygen from getting into the fridge.

The low temperature of the fridge slows enzyme activity.

The low temperature increases the number of bacteria

How does keeping food such as meat or fish in the fridge help to slow the rate of decomposition?

In most reactions, what will an increase in temperature result in?

What type of microscopic organisms carry out decomposition?

The reaction will increase as the temperature increases

The reaction increases until the enzyme starts to denature - the reaction slows

The enzyme works at the same rate whatever the temperature

The rate slows down as the temperature increases

In enzyme catalysed reactions, how will an increase in temperature affect the rate of the reaction?

When there are small numbers of collisions between the enzyme and substrate

When there is no substrate left for the enzyme to break down

What is meant by the 'optimum' temperature in an enzyme catalysed reaction?

Decomposers need water to carry out respiration

Decomposers need water in order to photosynthesise

Decomposers are aquatic organisms - they live in water

Decomposers secrete enzymes to break down organic matter and this requires water

Why are moisture levels important in the rate of decomposition?

Manure is broken down by the plants that grow in the soil.

The manure gets washed into the soil by rainfall. 

The manure is broken down by decomposers.

Nothing - it just helps to replace soil which may have been eroded.

What happens to manure (animal waste) that is put onto a field by a farmer? 

Starter Quiz

In most reactions, what will an increase in temperature result in?