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Biology · Chapter 1: Introduction to Biology
What is Biology?
Biology is the scientific study of living things. Learn what the word means, its three main divisions (botany, zoology and microbiology) and the seven characteristics of life.
Key termRememberExampleWatch out
01Concept
What does the word biology mean?
The word biology comes from two Greek words: bios, meaning life, and logos, meaning study. So, biology is the scientific study of living things.
A living thing is called an organism. Biologists study how organisms are built, how they work, how they grow and reproduce, and how they live together with other organisms and their surroundings.
The three main divisions of biology
| Division | What it studies | Example |
|---|---|---|
| Botany | Plants | How a mango tree makes its food |
| Zoology | Animals | How a camel survives in the Thar Desert |
| Microbiology | Microorganisms: living things so small they can be seen only with a microscope | Bacteria that turn milk into yogurt |
Characteristics of living things
How do we know if something is alive? All living things share a set of features called the characteristics of life. A living thing shows all of them, not just one or two.
- Nutrition: taking in food, or making it, to get energy and materials. Plants make their own food by photosynthesis; animals eat food.
- Respiration: releasing energy from food inside cells. This energy is used for every activity of life.
- Movement: changing position, or moving parts of the body. A sunflower slowly turns towards the Sun.
- Growth: a permanent increase in size, usually by making new cells.
- Reproduction: producing young ones (offspring) of the same kind. A hen lays eggs; a mango seed grows into a new tree.
- Excretion: removing waste substances that are made inside the body. We breathe out carbon dioxide and pass urine.
- Sensitivity: sensing changes around them (stimuli) and responding. You pull your hand away from a hot pan.
One more fact links all living things: every organism is made of one or more cells. The cell is the basic unit of life.
02Real World Examples
Growing more food
Biologists develop better varieties of crops such as wheat, rice and cotton, and find ways to protect them from pests. This helps farmers produce more food.
Health and medicine
Understanding how the body works helps doctors find the causes of diseases. Vaccines against polio and measles were made possible by biology.
Protecting wildlife
Biologists study endangered animals such as the Indus river dolphin and help protect them and their habitats.
Food in your kitchen
Making yogurt, bread and cheese depends on tiny living things: bacteria and yeast. Microbiology explains how they work.
03Practice Questions
Try to answer in your own words first, then open the model answer.
Short questions
Q1.Define biology. Where does the word come from?Show answer
Answer
Biology is the scientific study of living things (organisms).
The word comes from two Greek words: bios (life) and logos (study).
Q2.Name the three main divisions of biology and state what each one studies.Show answer
Answer
- Botany: the study of plants.
- Zoology: the study of animals.
- Microbiology: the study of microorganisms, such as bacteria.
Q3.What is meant by sensitivity in living things? Give one example.Show answer
Answer
Sensitivity is the ability to sense changes in the surroundings (stimuli) and respond to them.
Example: when you touch a hot object, you quickly pull your hand away.
Q4.Is a dry seed living or non-living? Give a reason.Show answer
Answer
A dry seed is living.
It contains a small living plant called an embryo. The seed is resting, and when it gets water, air and warmth it grows into a new plant.
Q5.Fire grows and uses oxygen. Why is it not considered a living thing?Show answer
Answer
Fire shows only a few features that look like life. It is not made of cells, it cannot reproduce by itself, and it does not respond to its surroundings like an organism.
A thing is living only if it shows all the characteristics of life.
Long questions
Q6.Describe the characteristics of living things. Give one example of each.Show answer
Answer
All living things share seven characteristics (remember MRS GREN):
- Movement: changing position or moving body parts. A sunflower turns towards the Sun.
- Respiration: releasing energy from food in cells. Our cells release energy from glucose.
- Sensitivity: responding to changes around them. We blink when dust comes near the eye.
- Growth: a permanent increase in size. A baby grows into an adult.
- Reproduction: producing offspring of the same kind. A hen lays eggs that hatch into chicks.
- Excretion: removing waste made in the body. We breathe out carbon dioxide.
- Nutrition: getting food for energy and materials. Plants make food by photosynthesis.
In addition, all living things are made of cells.