GED and HiSET science — life science

Life science is the largest science strand on the HiSET and, with physical science, one of the two largest on the GED, and the questions are rarely "what is a ribosome". They describe a situation and ask what follows from it. These twelve are written the same way.

So the cell questions arrive as failures: a cell whose ribosomes stop working cannot build proteins, and naming the organelle is only the first half of the answer. The food web arrives as arithmetic — producers capture ten thousand units of energy, the animals that eat them store one thousand, and the question is where the other nine thousand went. The genetics arrives as a cross described in a sentence, so that the chance of a recessive trait appearing can be worked out without drawing a square, which is worth practicing because the square is a tool for the reasoning and not the reasoning itself.

Three items are built around mistakes that are worth making once, in private. A deer herd is released on an island with no predators: it grows for three years and then collapses, because removing one limit leaves the others — food, water, disease — exactly where they were. Natural selection is asked so that the tempting answer is the one where individuals change their own traits to suit the conditions, which is not what happens; what changes is the makeup of the population over generations. And two cuttings from a single hydrangea, genetically identical, flower blue in one garden and pink in another, because acidic soil makes aluminum available to the plant and alkaline soil does not. The gene fixes what is possible; the conditions settle what appears.

The rest covers photosynthesis and respiration as the same exchange run in opposite directions, how the circulatory system depends on the respiratory one for the cargo it carries, homeostasis shown as a body correcting itself, how a vaccine teaches an immune system, and why a woodland that has lost five of its six pollinator species can look entirely healthy right up until the year the sixth has a bad season.

Every number is written into its sentence — the one cell drawing in the quiz illustrates a question that can be answered without it, so each question can be answered on paper or read aloud.

Zestly is an independent study tool. It is not affiliated with GED Testing Service, which owns the GED test, or with the HiSET program, and it is not a test center.

• Say what a cell can no longer do when a named organelle fails
• Explain how photosynthesis and cellular respiration reverse each other
• Account for the energy that does not pass from one level of a food web to the next
• Work out the chance of a recessive trait from a cross described in words
• Separate a gene from a trait, including a case where one genotype gives two results
• Explain how two body systems depend on each other, and what homeostasis looks like in action
• Say what limits a population once its predators are gone, and how natural selection changes a population rather than an individual
• Describe how a vaccine produces immunity, and why a loss of biodiversity matters before any damage is visible

Practice material written by Zestly; each figure is in its own sentence. From the bank: "In a food web, producers capture 10,000 units of energy from the sun. Primary consumers eat the producers, but only 1,000 units of that energy are stored in their bodies. What happens to the remaining 9,000 units?" The numbers are there so the loss between levels is something the candidate sees rather than recalls.