Characteristics of living organisms
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The teaching part (2 min) is free to watch. A free account opens the whole lecture: 3 worked examples, 5 practice questions, 2 real past-paper questions with the answers explained, the mistakes that lose marks, the full-marks tip, a one-card summary and a quick quiz.
What this lecture covers
- Alive or not?
- The seven characteristics
- The seven characteristics
- A memory trick
- Respiration is not breathing
- Excretion is not egestion
- Growth needs the word permanent
- Plants show all seven too
Read the transcript of the teaching part
Alive or not?
A car moves, uses fuel and gives out waste gases. A candle flame grows and needs oxygen. So are they alive? No. A living thing must show all seven characteristics of life, not just one or two of them.
The seven characteristics
Movement: an action by an organism, or part of an organism, that causes a change of position or place. Respiration: the chemical reactions in cells that break down nutrient molecules and release energy for metabolism. Sensitivity: the ability to detect and respond to changes in the internal or external environment. Growth: a permanent increase in size and dry mass.
The seven characteristics
Reproduction: the processes that make more of the same kind of organism. Excretion: the removal of waste products of metabolism, and substances in excess of requirements. Nutrition: taking in materials for energy, growth and development.
A memory trick
Here is a trick to remember all seven. MRS GREN. Movement, respiration, sensitivity, growth, reproduction, excretion and nutrition.
Respiration is not breathing
Respiration happens in every living cell. It is a set of chemical reactions that release energy. Breathing is only the movement of air in and out of the lungs. Plants and bacteria do not breathe, but they do respire. So breathing is not a characteristic of all living organisms. Respiration is.
Excretion is not egestion
Excretion removes waste made by the body's own reactions, such as carbon dioxide and urea. Egestion is getting rid of undigested food, faeces. That food was never part of the body's cells. Only excretion is a characteristic of life.
Growth needs the word permanent
A sponge soaking up water gets bigger, but that is not growth. The water can leave again. Growth is a permanent increase in size and dry mass, the mass with all the water removed. Dry mass is used because the amount of water in an organism changes from hour to hour.
Plants show all seven too
Plants move: leaves turn towards the light and flowers open and close. Plants show sensitivity: roots grow down towards gravity and shoots grow towards light. Plants make their own food by photosynthesis. That is their nutrition. And plants excrete oxygen, the waste product of photosynthesis, through their leaves.
How often it comes up
How often Cambridge has asked each part, counted by ExamYard from every past paper in its question bank: Characteristics of living organisms.
The whole chapter: Characteristics and Classification of Living Organisms.
Chapter 1: Characteristics and classification
- Characteristics of living organisms 5 min
- Naming species: the binomial system and DNA 5 min
- The five kingdoms and the vertebrate groups 5 min
- Ferns, flowering plants, viruses and keys 5 min
Also for IGCSE Biology 0610
Which topics come up most in IGCSE Biology 0610 past papers, counted from every paper since 2004.