Why do you look like your family?
Maybe you have your mother’s curly hair or your grandfather’s dimples. These features are called traits. Some traits are passed from parents to their young. Others come from experience.
Inherited traits
An inherited trait is passed from parents to offspring through information inside cells. You are born with them.
| Living thing | Examples of inherited traits |
|---|---|
| People | Eye colour, natural hair colour, freckles, blood type |
| Dogs | Coat colour, ear shape, size |
| Plants | Flower colour, leaf shape, height |
Acquired traits
An acquired trait is something a living thing gets during its life. It is not passed on to offspring.
- A scar from falling off a bike
- Strong muscles from exercise
- Short hair from a haircut
- A plant leaning toward a window
If a person dyes their hair blue, their children will not be born with blue hair!
Instincts and learned behaviours
Behaviours can be inherited too.
- An instinct is a behaviour an animal is born knowing. Spiders spin webs without being taught. Baby sea turtles crawl toward the ocean as soon as they hatch.
- A learned behaviour comes from experience. A dog learns to sit. A young bear learns to fish by watching its mother. You learned to read.
Variation
Offspring are similar to their parents, but not identical. Even brothers and sisters look different. These differences are called variation. Kittens in one litter may be striped, spotted or plain.
Variation is important. If the environment changes, some individuals may have traits that help them survive better.
Life cycles
All living things have a life cycle: birth, growth, reproduction and death.
Complete metamorphosis
Some insects go through metamorphosis, a big change in body form.
| Stage | Butterfly | Ladybug |
|---|---|---|
| Egg | Laid on a leaf | Laid near aphids |
| Larva | Caterpillar | Spiky larva |
| Pupa | Chrysalis | Pupa stuck to a leaf |
| Adult | Butterfly | Ladybug |
Incomplete metamorphosis
Grasshoppers and dragonflies have three stages: egg → nymph → adult. A nymph looks like a small adult without wings.
Other life cycles
- Frogs: egg → tadpole → froglet → adult
- Mammals: born alive → young → adult
- Flowering plants: seed → seedling → adult plant → flower → fruit and seeds
Comparing life cycles
| Butterfly | Frog | Human | |
|---|---|---|---|
| Starts as | Egg | Egg | Baby born alive |
| Big body change? | Yes | Yes | No |
| Number of stages | 4 | 4 | Grows gradually |
Common mistakes
- Thinking acquired traits are inherited. Learning to skateboard won’t make your children better skateboarders.
- Thinking all insects have four stages. Some have three.
Try it yourself
Sort these into inherited traits, acquired traits, instincts or learned behaviours:
- A bird building a nest
- A dog doing tricks
- Brown eyes
- A tattoo
- A baby crying when hungry
- Speaking French
Quick recap
- Traits are characteristics of living things.
- Inherited traits come from parents; acquired traits come from life experience.
- Instincts are inborn; learned behaviours come from experience.
- Offspring show variation; they are similar to but not the same as parents.
- Life cycles include birth, growth, reproduction and death, sometimes with metamorphosis.