BIOLOGY SUMMARIZED NOTES!!!!

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 CELLS
A cell is the smallest unit of life.
TYPES OF PLANT CELLS

1. Cell Wall – The cell wall is strong and stiff. It holds the plant cell in shape.
Plant cell walls are made of a substance called cellulose.

2. Cell Membrane – It controls what goes in and out of the cell.

3. Nucleus – Controls the activities of the cell.

4. Sap Vacuole – The liquid inside it is a solution of sugars and other substances
dissolved in water.

5. Mitochondria – Inside mitochondria, energy is released from food.

6. Chloroplasts—Plant cells that are in sunlight often contain chloroplasts. This is

where plants make their own food. It contains a green substance called
chlorophyll.

7. Cytoplasm—All cells have cytoplasm. Cytoplasm is like a clear jelly. Chemical

reactions happen inside the cytoplasm .
TYPES OF ANIMAL CELLS

1. Cell Membrane –It controls what goes in and out of the cell.
2. Nucleus: Controls the activities of the cell.
3. Cytoplasm: All cells have cytoplasm. Cytoplasm is like a clear jelly. Chemical
reactions happen inside the cytoplasm .
4. Mitochondria : Inside mitochondria, energy is released from food.

SPECIALIZED CELLS (ANIMAL CELLS)

1. Red Blood Cell –Red blood cells carry oxygen through the body using a
protein called hemoglobin.

Nerve Cell (Neuron) –Neurons are cells that send messages in the brain and body.

Muscle Cell—Muscle cells help the body move by contracting and relaxing.

Ciliated Cell –Ciliated cells move mucus and dust out of the lungs using tiny hair-
like structures.
KEY PARTS OF THE NERVE CELL.

● Axon – Long ber that carries messages away from the cell.

● Dendrites – Branches that receive signals from other cells.

SPECIALIZED (PLANT CELLS)

1. Root Hair Cell – Absorbs water and minerals from soil; has a long extension
for more surface area.

2. Palisade Cell – Found in leaves; packed with chloroplasts for photosynthesis.

CELLS, TISSUES AND ORGANS.

A group of similar cells, which all work together to carry out a particular function is
called a tissue.

A group of similar tissues, which work together to carry out a particular function is
called an organ.

A group of similar organs, which work together to carry out a particular function is
called an organ system.

A group of similar organ systems, which work together to carry out a particular
function is called an organism.
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 GROUPING AND IDENTIFYING ORGANISMS.

LIVING AND NON-LIVING

How do you check when something is alive?

1. Movement – Living things can move (even plants move slowly).

2. Respiration – Releasing energy from food.

3. Sensitivity – Responding to changes (like light, touch, or sound).

4. Growth – Getting bigger or changing shape over time.

5. Reproduction – Making more of the same kind (babies, seeds, etc.).

6. Excretion – Getting rid of waste (like sweat, urine, or gases).

7. Nutrition – Taking in or making food for energy.

VIRUSES
Viruses are tiny germs that can make people, animals, and even plants sick. They
are much smaller than bacteria and can’t be seen without a strong microscope.
Unlike living things, viruses can’t grow or reproduce on their own. They need to
enter a living cell to make more viruses.

You need to use a special microscope called electron microscope to see a

virus.

E.g Covid-19, in uenza etc

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SPECIES

A species is a group of living things that can have babies with each other, and their
babies can also grow up and have more babies. It’s a basic way scientists group
and name living organisms.

All the organisms in a species share the same characteristics but they are not
identical to each other.
Indian elephants reproduce only with other Indian elephants.
When they have offspring(children), the offspring belong to the same species as
their parents.
The young animals that are produced are called ligers. Ligers are healthy animals.
But ligers cannot reproduce. They are infertile.

USING KEYS
Biologists often want to identify an organism that they have found. Biologists also
use keys to help them to identify organisms. A key is a set of questions about the
organism you want to identify.
MICROORGANISMS
Microorganisms are tiny living things that are too small to be seen with the naked
eye. You need a microscope to see them. They live in water, soil, air, and even
inside our bodies. Some are helpful, and some can cause diseases.

1. Bacteria –
Single-celled organisms that can be good (like in digestion) or bad (cause
infections).

2. Viruses –
Tiny particles that are not alive on their own. They need to enter living cells to
multiply. They cause diseases like the u or COVID-19.

3. Fungi –
Can be single-celled (like yeast) or multi-celled (like molds and mushrooms).
Some are helpful (used in food), but others can cause infections.

4. Protozoa –
Single-celled organisms that live in water or inside animals. Some cause
diseases like malaria.

5. Algae –
Plant-like microorganisms that live in water. They make their own food using
sunlight (photosynthesis). Some are used in food or products.
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GROWING MICROORGANISMS

A single microorganism is too small to see without a microscope, but when left to
grow, a single of bacterium or fungus repeatedly to make a collection of many
cells.The collection of cells is called a colony. Scientists let microorganisms grow
in a Petri dish.

MICROORGANISMS IN THE ENVIRONMENT

● Microorganisms are tiny living things like bacteria, fungi, and tiny algae that
you can’t see without a microscope.

● They live in places like soil, water, and dead plants or animals.

Food Chain with Microorganisms:

● It starts with tiny plants like algae that make their own food using sunlight
(called producers).

● Then, tiny animals called protozoa eat these algae (these are called
consumers).

● Bigger tiny animals eat the smaller ones.

● When plants or animals die, microorganisms like bacteria and fungi break
them down. This is called decomposition.

● Decomposers help return nutrients to the soil or water, which helps plants
 ● Decomposers help return nutrients to the soil or water, which helps plants
grow again.

Food Web:

● A food web is like many food chains connected.

● Microorganisms are involved at many points: making food, eating, and

decomposing.

● This helps keep the environment healthy by recycling nutrients and keeping
energy moving.

The study of organisms in their environment is called ecology.

The rst organism in a food chain is a producer. Plants use energy from the Sun to
produce food.
All the other organisms in a food chain are consumers.
Consumers that consume only plants are called herbivores.
Consumers that consume only animals are called carnivores.
Animals that catch , kill and eat other animals are predators. The animals they eat
are their prey.

1. Algae Protozoa Small sh Big sh Bacteria

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Food webs

DECOMPOSERS AND DECAY

● Decomposers are living things that break down dead plants, animals, and
waste.

● Examples: Bacteria, fungi (like mold and mushrooms), and some insects or
worms.

● Decay is the process of breaking down dead things into simpler substances.

● This happens naturally over time and helps clean the environment.

Decomposers are important because:

● They recycle nutrients back into the soil.

● Help plants grow by making the soil rich.

● Keep the environment clean by breaking down waste

WHERE DOES DECAY TAKE PLACE?

● In soil, compost, forests, water, and anywhere dead things are found.

Things That Affect Decay:

1. Temperature – Warmth speeds it up.

2. Moisture – Wet conditions help decomposers work.

3. Oxygen – Many decomposers need air to break things down.