Year 8 Science · Unit 1 · Lesson 5
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Learning Goals
Match each structure to what it does
Write the matching letter in the middle column. Each letter is used once.
| Structure | Letter | What it does |
|---|---|---|
| Heart | A. Takes in oxygen and gets rid of carbon dioxide. | |
| Lungs | B. Contracts to pull on bones and move the body. | |
| Stomach | C. Pushes blood through the blood vessels. | |
| Leaf | D. Holds a plant in the soil and takes up water and minerals. | |
| Root | E. Churns food and starts to break it down. | |
| Muscle tissue | F. Uses light to make food for the plant. |
Odd one out
In each row, three items belong together and one does not. Circle the odd one out and give your reason.
| Row | Items | Reason |
|---|---|---|
| 1 | organ · chloroplast · cell · tissue | |
| 2 | bone tissue · the heart · a stem · a lung | |
| 3 | a gum tree · a kookaburra · a heart cell · an amoeba |
1. Write the five levels of organisation, starting with cell and ending with organism.
Classify and justify
Name the level of each example. Then give your reason by saying what it is made of.
| Example | Level | Reason: what it is made of |
|---|---|---|
| A blade of grass | ||
| The lining of the small intestine | ||
| One root hair cell | ||
| A dog’s digestive system |
A student writes
“An organ is just a big lump of tissue.”
2. Write a more accurate description of an organ. Use one plant organ and one animal organ as examples.
Read the data
A teacher marked 30 answers to the checkpoint question “Prove that a plant is a living system” (4 marks). She grouped the answers into three types and found the average mark for each type.
| Type of answer | What a typical answer said | Students | Average mark |
|---|---|---|---|
| List only | “Plants have roots, stems and leaves.” | 12 | 1.0 |
| Parts and jobs | “Roots absorb water, the stem holds the plant up, and leaves make food.” | 11 | 2.3 |
| Parts, jobs and links | “Roots absorb water, the stem carries it up to the leaves, and the leaves make food that is sent back to the roots.” | 7 | 3.6 |
Source: sample class results.
3. What percentage of the class wrote a “parts, jobs and links” answer? Round to the nearest whole number.
Answer %
4. Describe the pattern in Table 1. Then explain why the teacher gave the most marks to answers with links.
5. Rewrite the “list only” answer so that it would score 4 out of 4.
6. Choose one structure in a gum tree and one in a kookaburra. For each, describe what it does and which other part it relies on. Then use your two examples to argue that both are living systems, and state one real difference in how they are organised.
Match each structure to what it does
Heart → C; Lungs → A; Stomach → E; Leaf → F; Root → D; Muscle tissue → B.
Odd one out
Row 1: chloroplast (a structure inside a cell, not a level). Row 2: bone tissue (a tissue; the others are organs). Row 3: a heart cell (not a whole organism; an amoeba is a single-celled organism).
1. Cell, tissue, organ, organ system, organism. [1 mark]
Classify and justify
Blade of grass: organ; a leaf, made of several tissues. Lining of the small intestine: tissue; a layer of similar cells. Root hair cell: cell; one specialised cell. Dog’s digestive system: organ system; several organs working together.
2. An organ is made of several different tissues working together to do a major job; one kind of tissue on its own is only a tissue. The heart (muscle, nerve and lining tissue) pumps blood; a leaf (photosynthetic tissue and a protective outer layer) makes food. [3 marks: different tissues; plant example; animal example]
Read the data
3. 7 ÷ 30 × 100 = 23.3, so 23%. [2 marks] 4. The more an answer explained, the higher the mark: 1.0, then 2.3, then 3.6. Links score most because a system is defined by parts working together, so an answer must show how one part’s job supports another. [3 marks: pattern with data; links show interaction; meaning of a system]
5. Model: A plant is a living system because its parts work together. The roots anchor it and absorb water and minerals; the stem holds it up and carries water to the leaves; the leaves use light to make food, which is carried back to the roots. Each part depends on the others. [3 marks: three jobs; a link; a claim about the system]
Show What You Know
6. Marking guide: 1 both built from cells, tissues, organs and organ systems that work together; 2 a gum tree structure, its job and a dependence (leaves make food but need water brought up from the roots through the trunk); 2 a kookaburra structure, its job and a dependence (the heart pumps blood but needs the lungs to load it with oxygen); 1 a real difference (cell walls and chloroplasts; root and shoot systems instead of a heart or lungs; makes its own food, while the kookaburra must catch its food). [6 marks]
Common error to watch for: calling a blade of grass a tissue because it is thin. A leaf is an organ because it is built from several tissues.