Edexcel IGCSE Biology · Spec 1.2
Organism Groups: Required Features and Examples
Covers compare the required features of plants, animals and fungi, Recall how each group stores carbohydrate and Use named examples to identify organism groups.
Biology revision video
Organism Groups: Required Features and Examples
Prefer to watch on YouTube? Open this video on YouTube.
Explained
Telling the three groups apart on evidence
Plants, animals and fungi are all eukaryotic, so a nucleus does not separate them. Three other features do: the cell wall, how they feed, and what carbohydrate they store.
No single feature settles it. Both animals and fungi store glycogen, and both plants and fungi have cell walls, so you need a combination, and a question giving you several clues expects you to use several.
Plants
Multicellular. Cell walls made of cellulose. Many cells contain chloroplasts and photosynthesise, so they make their own food. They store carbohydrate as starch, and also as sucrose. Named examples in the specification are the maize plant and the pea plant.
Animals
Multicellular. No cell wall at all and no chloroplasts. They feed on other organisms and usually show nervous coordination and movement. They store carbohydrate as glycogen. Named examples are humans and houseflies.
Fungi
Cannot photosynthesise. Cell walls made of chitin, not cellulose. Most are multicellular with a body of threads called hyphae, often with many nuclei, forming a network called a mycelium. They store glycogen. Named examples are Mucor, which has the typical hyphal structure, and yeast, which is the single celled exception.
Saprotrophic nutrition
Fungi feed saprotrophically, which is worth being able to describe rather than just name.
They secrete enzymes out of the hyphae onto the food, the enzymes digest it outside the fungus, and the soluble products are then absorbed back in. Digestion happens outside the organism, which is why it is called extracellular digestion.
That is the opposite of an animal, which takes food inside first and digests it internally.
What the mark scheme accepts and rejects
An Edexcel International GCSE Biology multiple choice question asks which statement about Mucor is correct, and the mark scheme explains every wrong option individually. The answer is that Mucor is a eukaryotic organism with cell walls made of chitin. The others fail because Mucor does not have cellulose, and because Mucor is not a prokaryote.
A second part rules out further options on the same organism: Mucor does have cytoplasm, and Mucor does not have chloroplasts or starch.
Read together, those explanations are a checklist for the whole topic. Chitin not cellulose separates fungi from plants. No chloroplasts and no starch separates fungi from plants again. Eukaryotic separates it from bacteria. Cytoplasm is present in everything and separates nothing.
On another paper the mark scheme awards single marks for the cell wall of yeast and for glycogen as its storage carbohydrate, which is the same set of features asked in the other direction.
The lesson is that these are recall marks, decided by one word each. Chitin or cellulose. Starch or glycogen. Getting the pairing right is the whole question.
Working through an unfamiliar organism
Take the features one at a time and eliminate.
Multicellular with a cell wall and no chloroplasts, absorbing nutrients from dead material: the wall rules out an animal, the absence of chloroplasts rules out a plant, and saprotrophic feeding confirms a fungus.
Multicellular, no cell wall, moves towards food: no wall rules out plants and fungi, so it is an animal.
Say which feature rules out which group as you go. Naming the group without the evidence usually earns part of the credit only, because the question is testing the reasoning rather than the label.
Spec 1.2
What you need to know
- Compare the required features of plants, animals and fungi
- Recall how each group stores carbohydrate
- Use named examples to identify organism groups
Active recall
Quick check
Answer each question before opening the answer.
Which carbohydrate is stored by animals and fungi?
Glycogen
What is the cell wall of a fungus made from?
Chitin
How does a saprotrophic fungus obtain nutrients?
It secretes enzymes onto food and absorbs the soluble products of digestion
Biology revision app
Take this topic further in the app
275 guided topics with questions marked as you answer them, section checkpoints and timed practice papers. Fifteen topics are free to try, with no card needed.