The chapter describes the molecules that build cells and do their work: carbohydrates, proteins, lipids, nucleic acids and water. The four lessons turn that list into patterns you can explain.
This chapter is part of SPM Biology.
How do the four lessons connect?
Each lesson adds a question you can ask of any molecule.
- Comparing carbohydrates, proteins and lipids: what are they made of, and what do they do?
- Relating molecular structure to function: why does the shape or build suit the job?
- Interpreting food-test results conceptually: how do we show which molecule is present?
- Explaining the roles of water and nucleic acids: what do the last two groups do?
What does one meal show?
Take a plate of nasi lemak with egg. The rice supplies starch, a carbohydrate, which is broken down to glucose for energy. The egg gives protein for growth and repair, and the coconut milk and fried anchovies supply lipids, an energy store.
If you tested a piece of the rice with iodine solution, the colour would turn blue-black, showing starch. Your own cells carry DNA, which stores the instructions for making proteins, and water carries all of these dissolved substances around.
One plate contains every idea in the chapter.
Who should start where?
If you cannot yet say what a protein is built from, begin at lesson one. If you know the lists but cannot explain why a shape matters, go to lesson two. If practical questions on food tests cost you marks, start at lesson three.
Test yourself with the chemical composition of cells practice set.
When does extra help make sense?
Memory problems in this chapter come from learning each molecule in isolation. A teacher can build the comparisons with you and quiz you on the links.
If that would help, see online one-to-one Biology tuition and mention this chapter when you enquire.