K325 / 2027

Chapter 3 / 8 short lessons

Biological molecules

Connect food molecules to their roles, interpret food tests and explain how enzymes work.

G3 Pure Biology / K325 / 2027 syllabus

What do you think?

An enzyme reaction becomes slow in the cold. Must the enzyme be permanently damaged?

Lessons

0 of 8 marked as read
01

Carbohydrates, fats and proteins

State the main elements and roles of the three molecule groups.

About 4 min
About 4 min
02

Building larger molecules

Match each large molecule to the smaller units used to synthesise it.

About 5 min
About 5 min
03

Testing for starch and reducing sugars

Describe iodine and Benedict's tests and interpret their observations accurately.

About 5 min
About 5 min
04

Testing for proteins and fats

Describe biuret and ethanol emulsion tests, including valid observations and controls.

About 4 min
About 4 min
05

How enzymes speed up reactions

Explain specificity and enzyme action using the active site, enzyme-substrate complex and activation energy.

About 5 min
About 5 min
06

Temperature and enzyme activity

Explain temperature effects and compare rates using a controlled enzyme investigation.

About 6 min
About 6 min
07

pH and enzyme activity

Explain pH effects and plan a fair comparison of enzyme activity at different pH values.

About 5 min
About 5 min
08

Results tables, controls and errors

Draw a results table to the marked rules, set up a control with its reason, and state a source of error with its effect on the result.

About 7 min
About 7 min
What you will be able to do
  • Connect major biological molecules to their elements, units and roles.
  • Use food-test observations as evidence.
  • Explain enzyme action and investigate factors affecting its rate.

Spaced review

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