Explain it

01.05 — 6 short write-ups

Question 1 of 6

A checkpoint, not a test

Build a fair experiment

Answer from memory in a few sentences. This is practice, not the module exam.

A student measures bean plants arranged in two matching rows in a school greenhouse.
A fair test changes one factor and keeps the rest matched.
A student wants to know whether fertilizer changes bean-plant growth. Name the independent variable, dependent variable, control group, and one controlled variable that would make the test fair.

Use: change it, measure it, no treatment, keep it the same.

Question 2 of 6

A checkpoint, not a test

Theory and law are different jobs

Keep it short and exact. This is practice, not the module exam.

A student observes a pendulum experiment while recording repeated measurements.
Both theories and laws rest on repeated evidence.
Explain the difference between a scientific theory and a scientific law. Include what each one does, and say whether a theory turns into a law.

Think: explains versus describes.

Question 3 of 6

A checkpoint, not a test

Use the clues, not a guess

Two or three sentences is enough. This is practice, not the module exam.

A student compares food, oil, molecular models, and a DNA sample setup on a biology lab bench.
Structure and job are both evidence for identifying a macromolecule.
A molecule is built from amino acids and speeds up a chemical reaction. What kind of macromolecule is it, and which two clues support your answer?

Name the macromolecule, then use both clues from the question.

Question 4 of 6

A checkpoint, not a test

When heat changes an enzyme

Explain the cause and the result. This is practice, not the module exam.

A student compares test tubes in a rack and a controlled warm-water bath in a biology lab.
Temperature can change how well an enzyme works.
A human enzyme works normally at 37 °C but stops working after several minutes at a very high temperature. Explain what happened to the enzyme's shape and why the reaction slowed or stopped.

The course word for losing the working shape is denature.

Question 5 of 6

A checkpoint, not a test

First cells in a low-oxygen world

Connect the atmosphere to the kind of cells and respiration. This is practice, not the module exam.

A scientifically grounded reconstruction of a barren volcanic shoreline on early Earth.
Early Earth's atmosphere had little oxygen and no protective ozone layer.
Early Earth had very little oxygen. What kind of cells likely came first, why did anaerobic respiration fit those conditions, and what later process added oxygen to the atmosphere?

First cells, no-oxygen respiration, then photosynthesis.

Question 6 of 6

A checkpoint, not a test

What RNA showed

One short write-up. A few sentences is enough. This is practice, not the module exam.

A student researcher uses a micropipette beside an abstract single-stranded molecular display.
A molecular-biology lab studying RNA.
The old idea was that only proteins could be biological catalysts. What did RNA show about that idea?

You can look back at the 'two RNA costumes' section.