topic 1: key concepts in biology

Question 1

acrosome

Answer 1

an organelle in the tip of a sperm that contains enzymes which digest the egg cell membrane

Question 2

active site

Answer 2

a specific region on an enzyme where the substrate binds and the reaction takes place

Question 3

active transport

Answer 3

the movement of substances from a low concentration to a high concentration (against the concentration gradient) across a membrane, with the use of energy from respiration

Question 4

Benedict’s test

Answer 4

a chemical test used to test for reducing sugars that produces a different colour based on the amount of reducing sugar present

Question 5

biuret test

Answer 5

a chemical test that produces a purple colour when it is added to a solution containing protein

Question 6

carbohydrases

Answer 6

enzymes that break down carbohydrates into simple sugars

Question 7

carbohydrate

Answer 7

a large molecule that is synthesised from simple sugars

Question 8

cell

Answer 8

the basic building block of all living organisms

Question 9

cell membrane

Answer 9

a partially permeable barrier that surrounds the cell

Question 10

cell wall

Answer 10

an outer layer made of cellulose that strengthens plant cells

Question 11

chloroplast

Answer 11

an organelle that is the site of photosynthesis

Question 12

chromosome

Answer 12

a long, coiled molecule of DNA that carries genetic information in the form of genes

Question 13

cilia

Answer 13

hair like structures found on ciliated epithelial cells which waft substances across the surface of the tissue in one direction

Question 14

ciliated epithelial cell

Answer 14

a type of epithelial cell that lines the surface of structures such as the respiratory tract and uterus

Question 15

concentration gradient

Answer 15

the difference in concentration between two areas

Question 16

denaturation

Answer 16

upon exposure to high temperatures or extremes of pH, the permanent change in the shape of an enzymes active site that prevents the binding of the substrate

Question 17

diffusion

Answer 17

the net spreading out of particles from a high concentration to a lower concentration (down their concentration gradient)

Question 18

diploid cell

Answer 18

a cell that contains two copies of each chromosome (i.e. a full set of chromosomes)

Question 19

egg cell

Answer 19

a specialised female sex cell involved in reproduction

Question 20

electron microscope

Answer 20

a type of microscope that uses a beam of electrons, focused using magnets, to produce an image of a specimen. it has a higher magnification and resolution that a light microscope

Question 21

enzyme

Answer 21

a biological catalyst that increases the rate of reactions in living organisms

Question 22

eukaryotic cell

Answer 22

a type of cell found in plants and animals that contains a nucleus

Question 23

flagella

Answer 23

a long hair like structure found on bacterial cells that is used for cell movement

Question 24

haploid cell

Answer 24

a cell that contains a single copy of each chromosome (i.e. half the number of chromosomes)

Question 25

light microscope

Answer 25

a type of microscope that uses a series of lenses to magnify the visible light reflecting off a specimen

Question 26

lipases

Answer 26

enzymes that break down lipids into fatty acids and glycerol

Question 27

lipid

Answer 27

a large molecule that is synthesised from fatty acids and glycerol

Question 28

lock and key hypothesis

Answer 28

a theory that describes how substrates must be the correct shape to fit the active site of an enzyme

Question 29

magnification

Answer 29

the number of times bigger an image appears compared to the original object (image size = magnification x real size)

Question 30

micrometre (μm)

Answer 30

a quantitative unit of length. one micrometer is equal to x10⁻⁶ meter

Question 31

millimeter (mm)

Answer 31

a quantitative unit of length. one millimetre is equal to x10⁻³ meter

Question 32

mitochondria

Answer 32

an organelle that is the site of respiration

Question 33

nanometer (nm)

Answer 33

a quantitative unit of length. one nanometer is equal to x10⁻⁹ meter

Question 34

nucleus

Answer 34

an organelle found in most eukaryotic cells that contains the genetic material of the cell and controls the activities of the cell.

Question 35

organelle

Answer 35

a specialised structure found inside a cell

Question 36

osmosis

Answer 36

the diffusion of water molecules from a region of high water concentration to a region of lower water concentration across a partially permeable membrane

Question 37

percentage change in mass

Answer 37

the proportion of the mans of a substance that has changed over a set period

Question 38

picometer (pm)

Answer 38

a quantitative unit of length. one picometer is equal to x10⁻¹² meter

Question 39

plasmid

Answer 39

loops of DNA found in the cytoplasm of prokaryotic cells

Question 40

prokaryotic cell

Answer 40

a type of cell found in bacteria that does not contain a nucleus

Question 41

proteses

Answer 41

enzymes that break down proteins into amino acids

Question 42

rate of reaction

Answer 42

the speed at which reactants are converted into products

Question 43

resolution

Answer 43

the smallest distance between two objects that can be distinguished

Question 44

ribosomes

Answer 44

sub-cellular structures that are the site of protein synthesis

Question 45

specialised cell

Answer 45

a cell that has a structure which makes it adapted to its function

Question 46

specificity

Answer 46

describes the ability of an enzyme to catalyse only a particular reaction or set of reactions in which a specific substrate fits the active site of the enzyme

Question 47

sperm cell

Answer 47

a specialised male sex cell that is involved in reproduction

Question 48

vacuole

Answer 48

an organelle found in plant cells which stores cell sap and supports the cell