Life processes and unicellular organisms

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課程筆記

Life Processes (MRS GREN)

All living organisms perform seven life processes, remembered by the acronym MRS GREN.
Movement: All living things move; plants grow towards light, animals move to find food or escape danger.
Respiration: A chemical reaction that releases energy stored in glucose.
Sensitivity: Living things sense changes in their environment and respond (e.g., humans feel heat, plants grow towards light).
Growth: Organisms increase in size; unicellular organisms grow by increasing cell size, multicellular by producing more cells.
Reproduction: The process of producing offspring.
Excretion: The removal of waste products from the body.
Nutrition: Plants photosynthesise; animals eat plants or other animals.

Unicellular Organisms

Unicellular organisms are living organisms made of just one cell.
Despite their small size, they perform all seven life processes.
Examples include bacteria, euglena, amoebas, and yeast (a fungus).

Bacteria

Bacteria are some of the most common and diverse unicellular organisms.
They do not have a nucleus; genetic material is located in the nucleoid and plasmids.
Some bacteria have a long tail called a flagellum for movement.
Bacteria have a cell wall, cell membrane, and ribosomes.

Structure of a bacterium

Euglena

Euglena is a unicellular organism found in water.
It has a flagellum to help it swim.
It contains chloroplasts for photosynthesis.

Structure of Euglena

Other Unicellular Organisms

Amoebas are unicellular organisms that move and feed using pseudopods.
Yeast is a unicellular fungus used in baking and brewing.

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練習題

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1.How many life processes do all living organisms perform?
Easy
- ASeven
- BFive
- CSix
- DEight
2.Which of the following is NOT a life process?
Easy
- APhotosynthesis
- BRespiration
- CExcretion
- DSensitivity
3.Which statement about unicellular organisms is correct?
Easy
- AThey are made of one cell and perform all life processes.
- BThey are made of many cells and perform only some life processes.
- CThey are made of one cell and perform only some life processes.
- DThey are made of many cells and perform all life processes.
4.Which of the following is an example of a unicellular organism?
Easy
- ABacterium
- BHuman
- COak tree
- DMushroom
5.Bacteria do not have a nucleus. Where is their genetic material located?
Easy
- AIn the nucleoid and plasmids
- BIn the nucleus
- CIn the cytoplasm
- DIn the cell wall
6.What is the function of the flagellum in some bacteria?
Easy
- AMovement
- BRespiration
- CReproduction
- DNutrition
7.Euglena is a unicellular organism that can photosynthesise. Which organelle allows it to do this?
Easy
- AChloroplast
- BMitochondrion
- CNucleus
- DFlagellum
8.A student observes a unicellular organism under a microscope. It has a flagellum and chloroplasts. Which organism is it most likely to be?
Medium
- AEuglena
- BAmoeba
- CYeast
- DBacterium

複習筆記

## Life Processes and Unicellular Organisms All living organisms carry out **seven life processes**, remembered by the acronym **Mrs. Gren**: - **M**ovement: All living things move (e.g., plants grow towards light, animals move to find food). - **R**espiration: A chemical reaction that releases energy stored in glucose. - **S**ensitivity: Sensing changes in the environment and responding (e.g., humans feel heat, plants grow towards light). - **G**rowth: Increase in size (unicellular) or number of cells (multicellular). - **R**eproduction: Producing offspring. - **E**xcretion: Removing waste products from the body. - **N**utrition: Plants photosynthesise; animals eat plants or other animals. **Unicellular organisms** are living organisms made of just one cell. They perform all seven life processes. Examples include: - **Bacteria**: No nucleus; genetic material in nucleoid and plasmids. Some have a flagellum for movement. - **Euglena**: Found in water; has a flagellum for swimming and chloroplasts for photosynthesis. - **Amoeba** and **yeast** (a fungus). Key points: - Bacteria do **not** have a nucleus. - Euglena have chloroplasts (photosynthesis) and a flagellum (movement). - Not all living things carry out photosynthesis (only plants and some unicellular organisms like euglena).

Unicellular organism: A living organism made of just one cell.
Mrs. Gren: Acronym for the seven life processes: Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition.
Respiration: A chemical reaction that releases energy stored in glucose.
Flagellum: A long tail used for movement in some unicellular organisms (e.g., bacteria, euglena).
Nucleoid: Region in bacteria where genetic material is located (no nucleus).
Plasmid: Small circular DNA in bacteria, separate from the nucleoid.
Chloroplast: Organelle in euglena (and plants) that carries out photosynthesis.

字卡

What does the acronym MRS GREN stand for?

Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition.

What is a unicellular organism?

A living organism made of just one cell.

How many life processes do all living organisms perform?

Seven.

Define movement in the context of life processes.

All living organisms move in some way; plants move slowly towards light, animals move to find food or escape danger.

What is respiration?

A chemical reaction that releases energy stored in glucose.

Define sensitivity.

Living things can sense changes in their environment and respond to them.

How do unicellular organisms grow?

They grow by increasing in size.

What is reproduction?

The process of producing offspring.

Define excretion.

The process of removing waste products from the body.

How do animals obtain nutrition?

Animals need to eat plants or other animals.

How do plants obtain nutrition?

Plants photosynthesise.

Do bacteria have a nucleus?

No, bacteria do not have a nucleus.

Where is genetic material located in bacteria?

In the nucleoid and plasmids.

What is a flagellum?

A long tail used for movement, found in some bacteria and euglena.

Name three examples of unicellular organisms.

Bacteria, euglena, amoebas, and some fungi such as yeast.

What organelles does euglena have for movement and photosynthesis?

A flagellum for swimming and chloroplasts for photosynthesis.

True or false: All living organisms carry out respiration.

True.

True or false: All living organisms carry out photosynthesis.

False.

True or false: Unicellular organisms are made of more than one cell.

False.

True or false: Bacteria contain a nucleus.

False.

What is the purpose of the flagellum in bacteria?

Movement.

What is the purpose of chloroplasts in euglena?

Photosynthesis.

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