Hello, Young Scientist! Welcome to the Life Cycle Adventure!

Have you ever looked at a tiny puppy and wondered how it will grow into a big dog? Or seen a small seed and thought about how it becomes a tall tree? Everything that is alive, including you, goes on a special journey called a life cycle.

In these notes, we'll explore the amazing life cycles of humans (that's us!), animals, and plants. It's an exciting story of how living things are born, how they grow and change, and how they create new life. Let's begin our adventure!


Our Very Own Life Cycle: The Human Journey

Your Amazing Growth Story

Think about when you were a baby! You can ask your parents to show you a baby photo. What's different now?

During your childhood, you go through many changes. The syllabus points out a few big ones (1LC1):

  • You get taller and your height increases.
  • You get heavier and your weight increases.
  • Your first set of teeth, called milk teeth, fall out.
  • Your new, stronger teeth, called permanent teeth, grow in.

The Stages of Human Life

Our whole life is a journey with different stages. Everyone goes through them! (5LC1)

  • Infancy (Baby): From birth until about 2 years old. We learn to crawl, walk, and talk.
  • Childhood: From 2 to about 11 years old. This is you right now! You go to school, learn many things, and make friends.
  • Adolescence (Teenager): This is when we go through puberty. Our bodies change a lot as we prepare to become adults. We'll talk more about this!
  • Adulthood: We are fully grown. Many people get jobs and start their own families.
  • Old Age: The later stage of life. People have lots of experience and stories to share.

A Special Time of Change: Puberty

Don't worry if this seems new or tricky! Puberty is a natural and normal part of growing up from a child into an adult. Everyone goes through it, but we all do it at our own pace. (5LC2, 5LC4)

What Helps Us Grow and Stay Healthy?

During puberty, and all through life, certain things help our bodies grow strong and healthy. (5LC3)

  • Heredity: These are the traits passed down from your parents. It can affect how tall you might be.
  • Nutrition: Eating healthy food gives your body the fuel it needs to grow.
  • Sleep: Your body does a lot of growing and repairing while you sleep!
  • Exercise: Being active helps build strong muscles and bones.
Quick Review Box

Key Takeaway: Humans grow and change throughout their lives. The main stages are infancy, childhood, adolescence, adulthood, and old age. Puberty is a normal part of growing up, and things like good food, sleep, and exercise help us grow strong.


Amazing Animal Life Cycles

The Circle of Life

Just like us, all animals have a life cycle. It's a pattern that repeats. Most life cycles include these four stages (3LC1):

Birth -> Growth -> Reproduction (making new life) -> Death

Born from Eggs or from a Mother?

Animals start their lives in two main ways (3LC4):

  • Oviparous (Egg-Laying): These animals hatch from eggs. Examples: Chickens, frogs, butterflies, fish, and reptiles.
  • Viviparous (Live-Bearing): These animals are born live from their mother's body. Examples: Dogs, cats, cows, and humans!

Incredible Transformations!

Some animals look very different when they are babies compared to when they are adults. This big change is called metamorphosis. Let's look at the examples from the syllabus. (3LC2)

The Life Cycle of a Butterfly
  1. Egg: A tiny egg is laid on a leaf.
  2. Larva (Caterpillar): The egg hatches into a caterpillar. Its main job is to eat, eat, eat and grow!
  3. Pupa (Chrysalis): The caterpillar forms a protective case around itself. Inside, it completely changes its body!
  4. Adult: A beautiful butterfly emerges, ready to fly and lay its own eggs.
Did you know?

Inside the chrysalis, the caterpillar's body turns into a liquid, soupy-like substance before it reforms into a butterfly. It's like magic!

The Life Cycle of a Frog
  1. Egg: A frog lays its eggs in water, in a jelly-like bunch.
  2. Tadpole: The egg hatches into a tadpole. It lives in water, breathes with gills, and has a long tail for swimming.
  3. Froglet: The tadpole starts to grow legs and its tail gets shorter. It also develops lungs to breathe air.
  4. Adult Frog: The tail disappears, and it can now live on land and in water. It is ready to lay eggs.
Simpler Life Cycles

Not all animals have such dramatic changes!

  • Chicken: An egg hatches into a chick, which looks like a small, fluffy version of an adult chicken. It just gets bigger.
  • Dog: A mother dog gives birth to live puppies. The puppies look like small dogs and grow into adults.
Quick Review Box

Key Takeaway: All animals go through a life cycle of birth, growth, reproduction, and death. Some are born from eggs (oviparous) and some are born live (viviparous). Animals like butterflies and frogs go through a big change called metamorphosis. All life is precious, and we should respect and care for animals. (3LC5)


The Wonderful World of Plant Life Cycles

From a Tiny Seed to a Big Plant

Most flowering plants start their life as a tiny seed. A seed is like a sleeping baby plant with a packed lunch (food store) inside! Here are the stages of its life cycle (3LC3):

  1. Seed: The life cycle begins with a seed.
  2. Germination: With water, warmth, and air, the seed wakes up and starts to sprout. A small root grows down, and a small shoot grows up.
  3. Growth: The small plant, or seedling, grows bigger. It grows more leaves and a stronger stem and roots.
  4. Reproduction: The adult plant grows flowers. Flowers are very important because they help the plant make new seeds. (4LC1)
  5. Seed Dispersal: The plant spreads its seeds. They might be carried by the wind, water, or animals. The new seeds can then start the life cycle all over again!

Making New Plants Without Seeds!

This is so cool! Some plants don't need seeds to make new plants. They can grow a whole new plant from a part of the parent plant. This is another form of reproduction. (4LC2)

  • Growing from Roots: Examples: Carrots and sweet potatoes. If you plant them, they can grow a new plant.
  • Growing from Stems: Examples: Onions and garlic. These are special stems called bulbs that can grow into new plants.
  • Growing from Leaves: Examples: A Stone Lotus or Kalanchoe plant can grow tiny new plants right on the edges of its leaves!
Quick Review Box

Key Takeaway: A flowering plant's life cycle is often seed -> germination -> growth -> reproduction (flowering) -> seed dispersal. Some plants can also reproduce without seeds, using their roots, stems, or leaves.


Like Parent, Like Child: Passing on Traits

Why Do You Look Like Your Family?

Have you ever been told, "You have your mother's eyes" or "You have your father's smile"? This is because living things pass on their features, or traits, to their children. This is called heredity. The new babies are called offspring. (4LC4)

Offspring are similar to their parents, but not exactly the same. Think of it like a secret family recipe that gets passed down!

What Are Inherited Traits?

These are the traits you are born with because they are passed down from your parents. You can't change them! (4LC5, 4LC6)

Examples of Inherited Traits
  • In Humans: Your natural skin colour, eye colour, and whether your earlobes are attached or detached.
  • In Plants: The colour of the flower petals and the number of petals.
What Traits are NOT Inherited?

Some things about you are not from heredity. These are things that happen because of your environment or your choices.

  • Example from the syllabus: The length of your hair. You choose to cut it or grow it long!
  • Another example: If you get a scar from falling down, that is not inherited.

Can You Do This? A Fun Heredity Test!

Some inherited traits are really interesting! Try these out. (4LC6)

  • Tongue Rolling: Can you roll your tongue into a "U" shape? Some people can, and some can't. This is an inherited trait!
  • Hitchhiker's Thumb: Bend your thumb back. Does it stay straight, or does it curve backwards? This is also inherited.

Remember, it's just for fun! Whichever way your body is, it's perfectly normal.

Helping the Next Generation Survive

Living things have different ways to make sure their offspring have a good chance to survive and grow up. (4LC3)

  • Plants often produce a huge number of seeds. By making so many, they hope that at least a few will find a good spot to grow.
  • Mammals (like dogs and humans) usually have only a few babies at a time, but they take very good care of their young, protecting and feeding them until they are strong enough to survive on their own.
Quick Review Box

Key Takeaway: Living things pass traits to their offspring through heredity. Some traits are inherited (like eye colour), and some are not (like hair length). Living things have clever strategies, like making many seeds or caring for their young, to help their offspring survive.