Grade 8 CBC Science: Living Things and Their Environment

Flashcards covering basic biological definitions, light microscope parts and care, cell structures and functions, and plant versus animal cell comparisons.

What is a cell? it is a basic unit of life

The smallest basic unit of life and the basic building block of living organisms.

What is a unicellular organism?

An organism made up of only one cell.

What are examples of unicellular organisms mentioned in the notes?

Amoeba, Paramecium, and some bacteria.

What is a multicellular organism?

An organism made up of many cells.

What are examples of multicellular organisms mentioned in the notes?

Humans, fish, and trees.

What is a light microscope?

An instrument that uses visible light and lenses to magnify objects that are too small to be seen clearly with the naked eye.

What is the function of the arm on a light microscope?

Supports the upper parts and is used for carrying.

What is the function of the coarse adjustment knob on a light microscope?

Moves the tube/stage quickly for rough focus.

What is the function of the fine adjustment knob on a light microscope?

Makes small adjustments for sharp focus.

What is the function of the diaphragm on a light microscope?

Controls the amount of light passing through the specimen.

What is the function of the condenser on a light microscope?

Concentrates and directs light onto the specimen.

How should a light microscope be carried safely?

With two hands: one holding the arm and the other supporting the base.

What material should be used to clean microscope lenses?

Lens-cleaning paper/tissue only.

What substance makes up the rigid cell wall of a plant cell?

Cellulose.

What is the function of the cell wall?

Provides support, protection, and shape, and prevents excessive swelling.

What is the function of the cell membrane?

Controls movement of substances into and out of the cell.

What is the function of cytoplasm?

A jelly-like substance containing cell structures; it is the site of many chemical reactions.

What is the function of the nucleus?

A membrane-bound structure containing DNA that controls cell activities and contains genetic information.

What is the function of chloroplasts in plant cells?

Absorbs light energy and serves as the main site of photosynthesis.

What is the function of the large central vacuole in plant cells?

Stores substances and helps maintain cell turgidity.

What is the function of mitochondria?

Organelles with a folded inner membrane that act as the site of aerobic respiration, releasing energy from food.

What is the function of ribosomes?

Very small structures made mainly of RNA and proteins that serve as the site of protein synthesis.

What is the function of lysosomes?

Small membrane-bound structures containing digestive enzymes that break down unwanted materials and worn-out cell components.

What defines a cell as eukaryotic?

Having a true nucleus enclosed by a membrane.

Which five cell structures are present in both plant and animal cells?

Cell membrane, cytoplasm, nucleus, mitochondria, and ribosomes.

How do plant and animal cells differ in carbohydrate storage?

Plant cells store carbohydrates mainly as starch, whereas animal cells store carbohydrates mainly as glycogen.

What key features are present in plant cells but absent in animal cells?

Cell wall, chloroplasts, and a large central vacuole.