Definitions:Topic 3

Question 1

What is a light microscope(optical microscope)?

Answer 1

A tool that uses a beam of light and optical lenses to magnify specimens up to 1500 times life size.

Question 2

Define magnification.

Answer 2

A measure of how much bigger the image you see is than the real object.

Question 3

What is an electron microscope?

Answer 3

A tool that uses a beam of electrons and magnetic lenses to magnify specimens up to 500 000 times life size

Question 4

Define resolution(resolving power).

Answer 4

A measure of how close together two objects must be before they are seen as one.

Question 5

What are artefacts?

Answer 5

Things observed in a scientific investigation that are not naturally present; they occur as a result of the preparation or investigation

Question 6

What is a graticule?

Answer 6

A series of lines in the eyepiece of a microscope which help you measure specimens accurately.

Question 7

What is a transmission electron micrograph(TEM)?

Answer 7

Micrographs produced by the electron microscope that give 2D images like those from a light microscope, but magnified up to 500 000 times.

Question 8

What is a scanning electron micrograph(SEM)?

Answer 8

Micrographs produced by the electron microscope that have a lower magnification than TEMs, but produce a 3D image.

Question 9

Define cytoplasm.

Answer 9

A jelly-like liquid that makes up the bulk of the cell and contains the organelles

Question 10

Define the term ‘nucleus’.

Answer 10

An organelle containing the nucleic acids DNA (the genetic material) and RNA, as well as protein, surrounded by a double nuclear membrane with pores

Question 11

Define protoplasm.

Answer 11

The cytoplasm and nucleus combined

Question 12

Define the term ‘ultrastructure.’

Answer 12

The detailed organisation of the cell, only visible using the electron microscope

Question 13

Define the term ‘intracellular’.

Answer 13

Inside the cell

Question 14

Define the term ‘chromatin.’

Answer 14

The granular combination of DNA bonded to protein found in the nucleus when the cell is not actively dividing

Question 15

What is a nucleolus?

Answer 15

An extra-dense region of almost pure DNA and protein found in the nucleus; it is involved in the production of ribosomes and control of growth and division

Question 16

Define the term ‘mitochondria’.

Answer 16

Rod-like structures with inner and outer membranes that are the site of aerobic respiration

Question 17

Define the term ‘cristae’.

Answer 17

The infoldings of the inner membrane of the mitochondria which provide a large surface area for the reactions of aerobic
respiration

Question 18

Define the term ‘eubacteria’.

Answer 18

True bacteria(prokaryotic organisms)

Question 19

Define the term ‘centrioles’.

Answer 19

Bundles of tubules found near the nucleus and involved in cell division by the production of a spindle of microtubules that move the chromosomes to the ends of the cell

Question 20

What is a spindle?

Answer 20

A set of overlapping protein microtubules running the length of
the cell, formed as the centrioles pull apart in mitosis and meiosis

Question 21

What are 80S ribosomes?

Answer 21

The main type of ribosome found in eukaryotic cells, consisting of ribosomal RNA and protein, made up of a 60S and 40S subunit; they are the site of protein synthesis

Question 22

What are 70S ribosomes?

Answer 22

The ribosomes found in the mitochondria and chloroplasts of eukaryotic cells and in prokaryotic organisms

Question 23

Define the embosymbiotic theory.

Answer 23

A theory that suggests mitochondria and
chloroplasts originated as independent prokaryotic organisms that began living symbiotically inside other cells as endosymbionts

Question 24

What are lysosomes?

Answer 24

Organelles full of digestive enzymes used to break down worn-out cells or organelles or digest food in simple organisms

Question 25

Define apoptosis(programmed cell death).

Answer 25

The breakdown of worn-out, damaged or diseased cells by the lysosomes

Question 26

What is the endoplasmic reticulum(ER)?

Answer 26

A 3D network of membrane-bound cavities in the cytoplasm that links to the nuclear membrane and makes up a large part of the cellular transport system as well as playing an important role in the synthesis of many different chemical substances

Question 27

What is the rough endoplasmic reticulum(RER)?

Answer 27

Endoplasmic reticulum that is covered in 80S ribosomes and which is involved in the production and transport of proteins

Question 28

Define exocytosis.

Answer 28

The movement of large molecules out of cells by the fusing of a vesicle containing the molecules with the surface cell membrane; the process requires ATP

Question 29

What is the smooth endoplasmic reticulum(SER)?

Answer 29

A smooth tubular structure similar to RER, but without the ribosomes, which is involved in the synthesis and transport of steroids and lipids in the cell

Question 30

What is the Golgi apparatus?

Answer 30

Stacks of membranes that modify proteins made elsewhere in the cell and package them into vesicles for transport, and also produce materials for plant cell walls and insect cuticles