Science Study Notes: The Structure of Living Things


Hello, Science Explorers!

Welcome to our amazing journey into the world of living things! Have you ever wondered what makes you, a tree, and a buzzing bee different from a rock or your school bag? It's because you are all living things!

In these notes, we'll uncover the secrets of what it means to be alive. We'll look at the special parts that make up plants and animals, from the big parts we can see to the tiny building blocks we can't! It's going to be a fun adventure!



Part 1: What Makes Something ALIVE?

Living Things vs. Non-living Things

The world is full of amazing things! We can sort them into two big groups:

1. Living Things: These are things that are alive.
Examples: People, dogs, cats, fish, birds, trees, flowers, insects.

2. Non-living Things: These are things that have never been alive.
Examples: Rocks, water, the sun, your pencil case, a toy car.


The Secrets of Living Things

So, how can we tell if something is a living thing? Living things can do special things that non-living things can't!

All living things:

  • Grow and Develop: A tiny puppy grows into a big dog. A small seed grows into a tall tree. Living things change and get bigger over time.
  • Reproduce: This means they can make more of their own kind. Adult animals have babies, and plants make seeds that grow into new plants.
  • Respond to Stimuli: This is a fancy way of saying they react to things around them! If you touch a hot stove, you pull your hand away quickly. A plant might grow towards the sunlight. That's responding!
  • Need Air and Water to survive: All living things need things like air and water to stay alive. This is one of their basic living conditions.
  • Move: Animals can walk, run, swim, or fly. Even plants move, but very slowly (like turning their leaves to the sun).
Quick Review Box

Living Things (like a kitten): Can grow, have babies, react to touch, need water.
Non-living Things (like a toy kitten): Cannot grow, cannot have babies, does not react, does not need water.

Key Takeaway

Living things can grow, reproduce, and react to their environment, but non-living things cannot.



Part 2: Exploring the World of Plants!

Plants are amazing living things! They can't walk around, but they have different parts that do very important jobs. Think of a plant as a busy little factory!

The Main Parts of a Plant

Let's look at the three main structures and their functions:

1. The Roots:

  • Job 1: They are like an anchor. They hold the plant tightly in the ground so it doesn't fall over.
  • Job 2: They are like a straw. They absorb water and nutrients from the soil for the plant to drink.

2. The Stem:

  • Job 1: It's like the plant's backbone. It supports the plant and holds the leaves and flowers up towards the sunlight.
  • Job 2: It's like a delivery highway. It transports water and nutrients from the roots up to the leaves, and food from the leaves down to the rest of the plant.

3. The Leaves:

  • Job 1: They are the plant's kitchen! The leaves are where the plant makes its own food using sunlight, air, and water. Amazing!

What About Flowers?

Many plants have flowers, which are not just pretty! They have an important job: to help the plant reproduce. Here are the main parts of a flower:

  • Petals: These are the colourful parts that attract insects like bees and butterflies.
  • Sepals: These are the small green leaves at the base of the flower that protect the bud before it opens.
  • Stamen and Pistil: These are the parts in the middle of the flower that work together to make seeds.

Did you know? Plants can be sorted into two groups: flowering plants (like roses and sunflowers) and non-flowering plants (like ferns and mosses).

Key Takeaway

Each part of a plant—roots, stem, leaves, and flower—has a special job to help the plant live, grow, and reproduce.



Part 3: Exploring the Animal Kingdom!

Animals are another huge group of living things. They come in all shapes and sizes! Scientists have a clever way to sort them into two main groups.

The Great Backbone Divide!

The first big question to ask is: "Does it have a backbone?"

1. Vertebrates: These are animals WITH a backbone. You can feel your own backbone running down your back!
Examples: Fish, frogs, snakes, birds, and mammals (like us!).

2. Invertebrates: These are animals WITHOUT a backbone. They are often soft or have a hard shell on the outside.
Examples: Insects, spiders, snails, jellyfish, worms.


Let's Meet the Vertebrates!

The vertebrate group is divided into five smaller classes. Let's see what makes them special:

  • Mammals: They have hair or fur, breathe with lungs, and feed their babies with milk. (e.g., dogs, cats, monkeys, humans)
  • Birds: They have feathers, wings, and a beak. They lay eggs with hard shells. (e.g., eagles, sparrows, penguins)
  • Reptiles: They have dry, scaly skin, breathe with lungs, and most lay leathery-shelled eggs. (e.g., lizards, snakes, turtles, crocodiles)
  • Amphibians: They have moist, smooth skin. They live in water when they are young (as tadpoles) and on land as adults. (e.g., frogs, toads, salamanders)
  • Fish: They live in water, have gills to breathe, and have fins and scales. (e.g., goldfish, sharks, clownfish)

A Quick Peek Inside a Mammal

Using mammals as an example, let's look at some of the important structures inside their bodies. We have these too!

  • Bones: Give our body its shape and support, like a frame for a house.
  • Muscles: Work with bones to help us move, run, and jump.
  • Lungs: Help us breathe in air.
  • Heart: A powerful pump that sends blood all around our body.
  • Stomach: Where the food we eat is broken down and digested.
Key Takeaway

Animals can be sorted into vertebrates (with a backbone) and invertebrates (without). Vertebrates are further grouped into mammals, birds, reptiles, amphibians, and fish, each with unique features.



Part 4: The Tiniest Building Blocks - Cells!

Don't worry if this seems tricky at first! This is a super interesting topic.

Imagine building a giant castle with Lego bricks. The whole castle is the living thing (like a person or a plant), and each tiny Lego brick is a cell.

A cell is the basic unit of life. All living things are made of cells! They are so small that we can only see them with a powerful tool called a microscope.

Plant Cells vs. Animal Cells

Plants and animals are both made of cells, but their cells are a little different because they do different jobs.

What's Special about Plant Cells?

Plant cells have two special parts that most animal cells don't have.

1. The Cell Wall:

  • Imagine an animal cell is like a squishy water balloon. A plant cell is like that same water balloon, but placed inside a strong cardboard box. That "box" is the cell wall!
  • The cell wall is a tough, strong outer layer that gives the plant cell its box-like shape and provides support. It's why a tall tree can stand up straight!

2. Chloroplasts:

  • These are tiny green parts inside the plant cell. They are the "food factories"!
  • Chloroplasts are where the plant makes its food using sunlight. This is what makes leaves and stems green! Animal cells do not have these because animals get their food by eating.
Quick Review: Plant vs. Animal Cells

Animal Cells:

  • No cell wall (so they have a flexible shape)
  • No chloroplasts

Plant Cells:

  • Have a strong cell wall for support.
  • Have green chloroplasts to make food.
Key Takeaway

All living things are made of tiny cells. Plant cells are different from animal cells because they have a strong cell wall for support and green chloroplasts to make food.