VMBO Year 3 · Organs and cells · Section 1.1
Organisms
What are organisms, and how do we recognise life?
All living things are called organisms. We recognise them by their characteristics of life. This course distinguishes nine: growth, development, metabolism, nutrition, breathing or gas exchange, excretion, movement, responding to stimuli and reproduction. An organism does not have to show all these characteristics at every moment. An organism that has permanently stopped carrying out life processes is dead.
Metabolism and responding to the environment
Metabolism includes the chemical reactions in an organism, such as reactions that release energy from nutrients. Nutrition supplies substances needed by cells, and gas exchange supplies oxygen for aerobic respiration. Waste products are removed by excretion. Organisms detect stimuli, such as light or smells, and respond, for example by moving. This is called responding to stimuli.
Growth, development and reproduction
During growth, an organism becomes larger and usually heavier. Changes in its structure or how it functions are called development. Growth does not continue throughout every organism's entire life. Reproduction produces offspring and allows a species to continue existing.
Human life stages
Human development passes through different life stages, from infancy to old age. Each stage has typical patterns of growth and development. Young children learn physical skills such as walking or cycling. Mental and emotional development also takes place, including becoming more independent and forming your own opinions during adolescence.
Overview of life stages
The age ranges below are approximate: people develop at different rates.
- Infant, 0–1½ years: grows rapidly, learns to sit and respond to other people.
- Toddler, 1½–4 years: develops walking and language skills.
- Preschool child, 4–6 years: learns skills such as cycling and playing together.
- School-age child, 6–12 years: learns to read, write and work with numbers.
- Teenager, 12–18 years: experiences physical changes and new feelings during puberty.
- Young adult, 18–21 years: becomes increasingly independent.
- Adult, approximately 21–65 years: may work, form relationships and have children.
- Older adult, approximately 65 years onwards: ageing may bring physical or mental changes, although health and abilities vary greatly.
Glossary
- Breathing and gas exchange
- Taking in oxygen and releasing carbon dioxide; breathing ventilates the lungs, where gas exchange occurs.
- Young adult
- The approximate 18–21-year stage used here, in which increasing independence is important.
- Infant
- A child up to approximately 1½ years old, growing rapidly and learning to sit and respond to others.
- Movement
- A change in the position of an organism or its parts, sometimes in response to stimuli.
- Mental and emotional development
- Changes in thinking, learning and feelings.
- Growth
- Becoming larger and usually heavier.
- Preschool child
- A child aged approximately 4–6, developing skills such as cycling, using screens appropriately and playing together.
- Life stages
- Periods of human life with typical patterns of development.
- Characteristics of life
- Processes indicating life, such as growth, responding to stimuli, metabolism and reproduction.
- Physical growth and development
- Changes in the body's size, shape, proportions and functioning.
- Development
- Changes in an organism's structure or functioning.
- Older adult
- A person in the stage beginning at approximately 65; ageing can involve physical and mental changes.
- Organisms
- Living things that carry out life processes.
- Toddler
- A child aged approximately 1½–4, learning to talk, walk and perform simple activities.
- Teenager
- A young person aged approximately 12–18, often experiencing puberty, a growth spurt, developing sexual characteristics and new feelings.
- Responding to stimuli
- Reacting to detected changes, for example by activating muscles or glands.
- School-age child
- A child aged approximately 6–12, learning skills such as reading, writing and arithmetic.
- Metabolism
- All the chemical reactions that change substances into other substances within an organism.
- Excretion
- Removing metabolic waste products from the body.
- Nutrition
- Taking in substances needed for energy, growth and maintaining the body.
- Adult
- The life stage used here for approximately 21–65 years, which may include work and having children.
- Reproduction
- Producing offspring.