biology science test

MRS GREN

Movement, Respiration, Sensitivity, Growth, Reproduction, Excretion, Nutrition (characteristics of living things)

Cell

The basic unit of life; all living things are made of cells.

Unicellular organism

An organism made of only one cell (e.g., bacteria).

Multicellular organism

An organism made of many cells (e.g., humans, plants).

The 3 parts of Cell Theory

1. All living things are made of cells. 2. Cells are the basic unit of life. 3. All cells come from existing cells.

Levels of organisation in living things

Cells → Tissues → Organs → Systems → Organisms

Nucleus

Controls cell activities and contains DNA.

Cytosol

Jelly-like fluid where cell reactions take place.

Cell membrane

Controls what enters and exits the cell.

Mitochondria

Produces energy for the cell through respiration (powerhouse of the cell).

Ribosomes

Makes proteins.

Vacuole (animal)

Small, stores nutrients and waste.

Vacuole (plant)

Large, stores water, nutrients, and waste.

Cell wall

Provides structure and support (only in plant cells).

Chloroplasts

Site of photosynthesis; contains chlorophyll (only in plant cells).

Only plant cells have

Cell wall, chloroplasts, large vacuole, defined shape

Coarse focus knob

Brings the image roughly into focus under low power.

Fine focus knob

Sharpens the image under higher power.

Objective lens

Provides different levels of magnification

Eyepiece

The lens you look through, 10x magnification

Stage

Holds the slide in place

Light source

Illuminates the specimen from below

How to prepare a wet mount slide

Add water/stain to the specimen, place cover slip at an angle to avoid air bubbles.

Why use stains?

To make cell structures more visible under the microscope.

Steps to view a slide under a microscope

Start on low power, use coarse focus, then switch to high power and use fine focus.

Total magnification

Eyepiece magnification × Objective lens magnification.

Effect of increasing magnification

Image gets larger, field of view decreases.

What happens when you move a slide left?

Image appears to move right (opposite direction).

Rules for drawing cells

Use pencil, clear outlines, no shading, label neatly with straight lines.