1.1 Characteristics of Living Organisms

1. Movement

Cambridge Definition:

Movement is an action by an organism or part of an organism causing a change of position or place.

Key Points:

1. Movement can involve the whole organism or only a part of an organism.
2. Animals move from one place to another using muscles and limbs.
3. Plants cannot move from place to place, but parts of plants can move in response to stimuli.

2. Respiration

Cambridge Definition:

Respiration is the chemical reactions in cells that break down nutrient molecules and release energy for metabolism.

Key Points:

1. Respiration occurs in all living cells.
2. Nutrient molecules, mainly glucose, are broken down.
3. Energy released is used for metabolism.

Uses of Energy Released:

1. Growth.
2. Active transport.
3. Movement.
4. Cell division.
5. Repair.
6. Synthesis of new molecules.

Exam Warning:

Respiration is not breathing.

1. Breathing = movement of gases into and out of an organism.
2. Respiration = chemical reactions inside cells.

3. Sensitivity

Cambridge Definition:

Sensitivity is the ability to detect and respond to changes in the internal or external environment.

A change that causes a response is called a stimulus.

Examples:

Animals:

1. Pupil becomes smaller in bright light.
2. Hand moves away from a hot object.

Plants:

1. Shoots grow towards light.
2. Roots grow towards gravity.

4. Growth

Cambridge Definition:

Growth is a permanent increase in size and dry mass.

Key Points:

Growth occurs due to:

1. Cell division.
2. Cell enlargement.

Growth requires:

1. Nutrients.
2. Energy from respiration.

Important Exam Point:

Growth is measured using dry mass because water content can change without true growth occurring.

Example:

A plant absorbing water becomes heavier, but this is not growth because dry mass has not increased.

5. Reproduction

Cambridge Definition:

Reproduction is the processes that make more of the same kind of organism.

Importance of Reproduction:

1. Produces new organisms.
2. Prevents extinction of species.
3. Allows species to continue through generations.

Types of Reproduction:

Sexual reproduction:

1. Two parents involved.
2. Fusion of male and female gametes.
3. Produces genetic variation.

Example:

1. Humans.

Asexual reproduction:

1. One parent involved.
2. No fusion of gametes.
3. Produces genetically identical offspring.

Example:

1. Bacteria.

6. Excretion

Cambridge Definition:

Excretion is the removal of the waste products of metabolism and substances in excess of requirements.

Examples of Excretory Products:

Exam Warning:

Do not confuse “Excretion with Egestion”

Excretion:

Removal of metabolic waste.

Example:

1. Carbon dioxide.
2. Urea.

Egestion:

Removal of undigested food.

Example:

1. Faeces.

7. Nutrition

Cambridge Definition:

Nutrition is the taking in of materials for energy, growth and development.

Plants:

1. Make their own organic nutrients by photosynthesis.
2. Use carbon dioxide, water and light energy.

Animals:

1. Obtain nutrients by feeding on other organisms.

Examiner Tips – 1.1 Characteristics of Living Organisms

1. Learn the Cambridge definitions exactly, especially respiration and excretion.
2. Remember respiration is a chemical process in cells, not simply breathing.
3. Excretion involves metabolic waste, not undigested food.