key concepts in biology

Question 1

what type of cell is a bacterial cell?

Answer 1

prokaryotic

Question 2

what type of cells are animal and plant cells?

Answer 2

eukaryotic

Question 3

what things are in both plant and animal cells and what are their functions?

Answer 3

• nucleus: contains cells dna
• cytoplasm: where chemical reactions take place
• cell membrane: controls what enters and leaves the cell
• mitochondria: where respiration occurs
• ribosomes: where protein synthesis occurs

Question 4

what other things are only in plant cells and what are their functions?

Answer 4

• chloroplasts: where photosynthesis happens
• vacuole: contains cell sap
• cell wall: provides the cell with strength

Question 5

which 6 things are found in a bacterial cell and what are their functions?

Answer 5

• cytoplasm: where chemical reactions take place
• cell membrane: controls what enters and leaves the cell
• cell wall: provides structure
• chromosomal dna: floats in cytoplasm due to no nucleus
• plasmids: rings of dna
• flagella: tail used for movement

Question 6

what do cells specialise through?

Answer 6

differentiation

Question 7

what are the 3 types of specialised cells in animals?

Answer 7

• sperm cell: carries male dna to the egg cell for reproduction
• egg cell: binds with sperm cell to develop into an embryo
• ciliated epithelial cell: traps mucus from going into the stomach

Question 8

what are the 3 types of specialised cells in plants?

Answer 8

• root hair cells: take up water by osmosis and mineral ions by active transport from the soil
• xylem cells: transport water and mineral ions up the plant from the roots to the shoots
• phloem cells: carry products of photosynthesis to all parts of the plants

Question 9

what is the difference between light microscope and electron microscopes?

Answer 9

light microscope: use light to view things, cannot view living cells
electron microscope: uses electrons to view things, can view living cells and very small bacterias

Question 10

when placed magnifications on each other, which one always goes on the objective lens?

Answer 10

the bigger number

Question 11

what is the equation for magnification?

Answer 11

image size= actual size x magnification

Question 12

what are the units for?:
- centimetres:
- millimetres:
- micrometres:
- nanometres:

Answer 12

• centimetres: 1x10^-2
• millimetres: 1x10^-3
• micrometres: 1x10^-6
• nanometres: 1x10^-9

Question 13

how do you prepare a microscope slide?

Answer 13

• take off a thin layer the sample
• add a stain (iodine) to make it more visible
• put them on the slide
• place a cover slip on top

Question 14

what are enzymes?

Answer 14

biological catalysts that speed up a reaction without being used up

Question 15

how do enzymes work?

Answer 15

the substrate fits onto the active site of an enzyme making an enzyme substrate complex which leads to the making of products

Question 16

how does temperature affect the enzyme activity?

Answer 16

when the temperature is too low, the enzyme activity is low due to not enough energy
when the temperature gets higher, the enzyme activity reaches the optimum (the best)
when the temperature gets too hot, enzyme activity decreases as the enzyme has denatured

Question 17

how does pH affect enzyme activity?

Answer 17

if the pH is too low or too high the enzyme activity decreases because the enzyme has denatured
if the pH reaches the optimum the enzyme activity is at its best

Question 18

how does substrate concentration affect enzyme activity?

Answer 18

as the substrate concentration increases the enzyme activity also increases but soon it stops increasing due to the active site being filled up

Question 19

how do you calculate the rate of a reaction?

Answer 19

rate of reaction= change/time

Question 20

what do lipase break down to produce?

Answer 20

lipase break down fats into fatty acids/glycerol

Question 21

what does protease break down to produce?

Answer 21

protease breaks down proteins into amino acids

Question 22

what does amylase break down to produce?

Answer 22

amylase breaks down starch into sugars

Question 23

what is the test for starch?

Answer 23

add iodine, if present it will go from orange to blue/black

Question 24

what is the test for reducing sugars?

Answer 24

add benedicts solution and heat for 2 minutes, if present it goes red

Question 25

what is the test for proteins?

Answer 25

add biuret solution, if present it goes from blue to purple

Question 26

what is the test for lipids?

Answer 26

add ethanol, add to a test tube of distilled water, if present a while emulsion forms on the surface

Question 27

what is diffusion?

Answer 27

net movement of particles from a high concentration to a low concentration

Question 28

what is osmosis?

Answer 28

the movement of water from a high solute concentration to a low solute concentration through a semi permeable membrane

Question 29

what is active transport?

Answer 29

movement across a membrane from a low concentration to a high concentration

Question 30

what is the practical for osmosis?

Answer 30

• cut up potatoes into small discs of equal sizes
• measure initial mass of each disc
• place them into the different concentrations of solutions
• dry with tissue and measure mass