Definitions

Question 1

Magnification

Answer 1

The degree to which the size of an image is larger than the object itself. Numerically, it is the image size divided by the actual size measured in the same units.

Question 2

Resolution

Answer 2

The degree to which it is possible to distinguish between two objects that are very close together. The higher the resolution, the greater the detail that can be seen.

Question 3

Staining

Answer 3

Any process that helps to reveal or distinguish different features. In light microscopy, stains may be coloured or fluorescent dyes. In electron microscopy, they are heavy metal salts.

Question 4

Cytoskeleton

Answer 4

Network of protein fibres found within cells that gives structure and shape to the cell, and also moves organelles around inside cells.

Question 5

Organelle

Answer 5

A particular structure of a cell that has a specialised function. Some organelles are membrane-bound, others are not. All perform a particular role in the life processes of the cell.

Question 6

Division of labour

Answer 6

Any system where different parts perform specialised functions, each contributing to the functioning of the whole.

Question 7

Phospholipid bilayer

Answer 7

The basic structural component of plasma membranes (cell surface membranes). It consists of two layers of phospholipid molecules. Proteins are embedded in this layer.

Question 8

Fluid mosaic model

Answer 8

The model of cell membrane structure. The lipid molecules give fluidity and proteins in the membrane give it a mosaic (patchwork) appearance. The molecules can move about.

Question 9

Cell signalling

Answer 9

Cells communicate with one another by signals. Many molecules act as signals - some signal during processes taking place inside cells; others signal from one cell to another. Cytokines are an example of cell signals.

Question 10

Diffusion

Answer 10

The passive net movement of molecules from a region of higher concentration to a region of lower concentration down a potential gradient.

Question 11

Active transport

Answer 11

The movement of molecules or ions across membranes, which uses ATP to drive protein ‘pumps’ within the membrane.

Question 12

Hypertonic

Answer 12

A solution with a lower water potential (higher solute concentration) compared to the cell.

Question 13

Hypotonic

Answer 13

A solution with a higher water potential (lower solute concentration) compared to the cell.

Question 14

Isotonic

Answer 14

A solution with the same water potential (same solute concentration) compared to the cell.

Question 15

Osmosis

Answer 15

Passive net movement of water across a partially permeable membrane from an area of higher water potential to an area of lower water potential, down the water potential gradient.

Question 16

Cell cycle

Answer 16

The events that take place as one parent cell divides to produce 2 daughter cells which then grow to full size. For single-celled organisms, the cell cycle is the life cycle, and each daughter cell is an offspring.

Question 17

Mitosis

Answer 17

The process of nuclear division where 2 genetically identical nuclei are formed from 1 parent cell nucleus, producing 2 daughter cells that are genetically identical.

Question 18

Meiosis

Answer 18

The process of nuclear division where 4 genetically different nuclei are formed from 1 parent cell nucleus, producing 4 daughter cells that are genetically different.

Question 19

Homologous pair

Answer 19

Chromosomes that have different versions of the same genes at the same loci (alleles). All chromosomes in a diploid organism come in pairs and those produced by sexual reproduction have one from the father and one from the mother, creating variation.

Question 20

Clones

Answer 20

Cells and organisms that are genetically identical to the parent.

Question 21

Differentiation

Answer 21

The changes that occur in cells of a multicellular organism so that each different type of cell becomes specialised to perform a specific function.

Question 22

Stem cells

Answer 22

Undifferentiated cells that are capable of becoming differentiated to a number of possible cell types.

Question 23

Tissue

Answer 23

A group of similar cells that perform a particular function.

Question 24

Organ

Answer 24

A collection of tissues that work together to perform a specific overall function or set of functions within a multicellular organism.

Question 25

Organ system

Answer 25

A number of different organs working together to perform an overall life function in a multicellular organism.

Question 26

Tidal volume

Answer 26

The volume of air moved in and out of the lungs with each breath at rest. It’s approximately 0.5 dm^3.

Question 27

Vital capacity

Answer 27

The largest volume of air that can be moved into and out of the lungs in any one breath. It’s approximately 5 dm^3.

Question 28

Residual volume

Answer 28

The volume of air that always remains in the lungs, even after removing the expiratory reserve. It’s approxiamtely 1.5 dm^3.

Question 29

Dead space

Answer 29

The air in the trachea, bronchi and bronchioles not involved in gas exchange.

Question 30

Inspiratory reserve

Answer 30

The maximum amount of air that can be inspired over the tidal volume during a deep breath.

Question 31

Expiratory reserve

Answer 31

The maximum amount of air that can be expired under the tidal volumed when breathing out as hard as possible.

Question 32

Single circulatory system

Answer 32

A circulation in which blood flows through the heart once during each circulation of the body.

Question 33

Double circulatory system

Answer 33

A transport system in which blood travels twice through the heart for each complete circulation of the body.

Question 34

Open circulatory system

Answer 34

Blood is not located inside vessels and instead bathes the tissue directly.

Question 35

Closed circulatory system

Answer 35

Blood is always located inside vessels and is pumped around the body at high pressure.

Question 36

Transpiration

Answer 36

Loss of water by evaporation from the aerial parts of a plant.

Question 37

Xerophyte

Answer 37

A plant that is adapted to reduce water loss so that it can live in arid conditions.

Question 38

Source

Answer 38

An area that releases sucrose into the phloem.

Question 39

Sink

Answer 39

An area that removes sucrose from the phloem.