the basic unit of life part 1 {module 3}

Question 1

() are the building blocks of all living organisms. Organisms can be made up of only a single () or of many () that are organised into different tissues. Each () is specialised to perform metabolic functions and to maintain a constant internal chemical balance known as homeostasis.

Answer 1

cells

Question 2

() was the first scientist to describe the cells and bacteria he observed under a microscope. (1675-1700)

Answer 2

Anton van Leeuwenhoek

Question 3

A cylinder containing two or more lenses. - These lenses are held at the correct working distance. helps to bring the object into focus.

Answer 3

Eyepiece/ocular lens

Question 4

() piece holds the objectives in place so that they can rotate and can be changed easily.

Answer 4

Revolving nose piece

Question 5

() magnifies the objects. There are normally three present: 4X magnification 10X magnification 40X magnification

Answer 5

Objective

Question 6

() screw is used for the initial focus of the object, by moving the stage up and down, bringing the object closer to or further away from the objective lens.

Answer 6

Coarse adjustment screw

Question 7

() is used for the final and clear focus of the object

Answer 7

Fine adjustment screw

Question 8

A rigid structure for stability. - is supported by a U-shaped foot leading to the base of the microscope.

Answer 8

frame

Question 9

Provides a source of light so that the object can be viewed

Answer 9

Mirror/light source

Question 10

controls the amount of light that passes through the slide.

Answer 10

Diaphragm/ Condenser

Question 11

The microscope slide is placed here. contains a clip or clips to prevent the slide from moving around. - There is a hole in the () that allows light through.

Answer 11

Stage

Question 12

() microscope was used to see images in three dimensions at a low resolution. It is still used and useful for low-level magnification of live tissue.

Answer 12

The light/dissecting microscope

Question 13

are large and expensive microscopes. They have much higher magnifying power than light microscopes and, therefore, allow us to see even smaller structures. Like the structures inside a cell e.g. mitochondria and chloroplasts.

In the 1950s, () were widely used for research.

An () uses a beam of electrons that are focused by electromagnets to magnify objects instead of light rays and lenses.

Answer 13

The electron microscope

Question 14

was first developed and focuses on electrons through thin slices of cells to magnify them millions of times. The electron beams pass through the surface of the material

Answer 14

Transmission electron microscopes (TEM)

Question 15

scan the surface of cells. The electrons bounce off the surface of the material producing a detailed image

Answer 15

Scanning electron microscopes (SEM)

Question 16

formula to calculate magnification

Answer 16

power of eyepiece x magnifying power of objective lens

Question 17

formula for field of view

Answer 17

current magnification/new magnification x current field of view

Question 18

formula to determine actual size of specimen

Answer 18

measured size x (true length of scale line/measured length of scale line)

Question 19

a piece of clear glass that is placed over the specimen on the slide.

Answer 19

Coverslip

Question 20

this is when the specimen that is going to be viewed is placed in a drop of water or other liquid

Answer 20

Wet mount