Topic 1- Key Concepts In Biology

Question 1

Definition of Eukaryotes

Answer 1

Eukaryotic cells are complex eg. animal and plant cells

Question 2

Definition of Prokaryotes

Answer 2

Prokaryotic cells are smaller and simpler eg. bacteria cells

Question 3

Function of the nucleus

Answer 3

contains genetic material that controls the activities of the cell

Question 4

Function of the cytoplasm

Answer 4

gel-like substance where most of the chemical reactions take place. It contains enzymes that control these reactions

Question 5

Function of the cell membrane

Answer 5

holds the cell together and controls what goes in and out

Question 6

Function of the mitochondria

Answer 6

these are where most of the reactions for respiration take place

Question 7

Function of the ribosomes

Answer 7

these are involved in translation of genetic material in the synthesis of proteins

Question 8

Function of the cell wall

Answer 8

it supports and strengthens the cell (plant cells)

Question 9

Function of the large vacuole

Answer 9

contains cell sap, it maintains the internal pressure to support the cell (plant cells)

Question 10

Function of the chloroplasts

Answer 10

these are where photosynthesis occurs, which makes food for the plant. they contain a green substance called chlorophyll (plant cells)

Question 11

Function of the flagellum

Answer 11

a long hair-like structure that rotates to make the bacterium move (bacteria)

Question 12

Function of the plasmid DNA

Answer 12

small loops of extra DNA that aren’t part of the chromosome. plasmids contain genes for things like drug resistance and can be passed between bacteria

Question 13

Function of the egg cell (3 ways it’s adapted to it function)

Answer 13

The main functions of an egg is to carry female DNA and nourish the embryo in the early stages

1) it contains nutrients in the cytoplasm to feed the embryo
2) it has a haploid nucleus
3) straight after fertilisation its membrane changes structure to stop any more sperm getting in

Question 14

Function of the sperm cell (4 ways it’s adapted to its function)

Answer 14

To transport male DNA to the female’s egg

1) has a long tail so it can swim
2) has lots of mitochondria in the middle so it has enough energy
3) it also has an acrosome at the front where it stores enzymes needed to digest its way through the membrane of the egg cell
4) it has a haploid nucleus

Question 15

Function of ciliated epithelial cells

Answer 15

To move substances in one direction along the tissues, they line the surfaces of organs and have hair like structures

Question 16

Equation for magnification

Answer 16

Magnification=image size/real size

Question 17

Equation for total magnification

Answer 17

Total magnification = eyepiece lens magnification X Objective lens magnification

Question 18

Differences between light and electron microscope

Answer 18

Electron
•higher resolution 
•higher magnification 
•black and white images
•can’t view living cells

Light
•lower resolution 
•lower magnification 
•colour images 
•can view living cells

Question 19

Definition of catalysts

Answer 19

A catalyst is a substance which changes the rate of reaction but is unchanged at the end of the reaction

Question 20

Definition of active site

Answer 20

• Every enzyme has an active site

* Active site is the part where it joins on to its substrate to catalyse the reaction

Question 21

Definition of optimum

Answer 21

Where the enzyme is most active

Question 22

what happens when enzymes get too hot or cold?

Answer 22

It denatures

Question 23

what do carbohydrates covert into?

Answer 23

Simple sugars

Enzymes called carboghydrases convert carbohydrates into simple sugars

Question 24

what do proteases covert into?

Answer 24

Amino acids

Proteases convert proteins into amino acids.

Question 25

what do lipases covert into?

Answer 25

Fatty acids

Lipases convert lipids into glycerol and fatty acids.

Question 26

how to test for sugars

Answer 26

Benedict’s reagent

• add Benedict’s reagent to a sample
• heat in a water bath at 75c
• if there’s sugar a coloured precipitate will form
• the higher the concentration of sugar the further the colour changes |

Blue -> green -> yellow -> orange-> brick red

Question 27

how to test for starch

Answer 27

Iodine

• if starch is present the sample turns dark blue/ black
• if not present it stays browny-orange

Question 28

how to test for lipids

Answer 28

• shake the substance with ethanol for a minute (until it dissolves)
• then add to water
• if lipids are present they will precipitate out of the liquid and show up as milky emulsion

Question 29

how to test for proteins

Answer 29

Buret test
•add a few drops of potassium hydroxide (to make it an alkaline)

•then add copper(II) sulphate solution (bright blue)

If there’s protein the solution will turn purple
If there’s no protein it will remain blue

Question 30

Equation for energy in food

Answer 30

Energy in food (J) = mass of water(g) x temperature change of water (°C)

Question 31

Equation for energy per gram

Answer 31

Energy per gram of food(J/g) = energy in food (J) ÷ mass of food (g)

Question 32

Definition for diffusion

Answer 32

Diffusion is the net (overall) movement of particles from an area of higher concentration to an area of lower concentration.

Question 33

Definition for osmosis

Answer 33

is the net movement of water molecules across a partially permeeble membrane from a region of higher water concentration region of lower water concentration.

Question 34

Definition for active transport

Answer 34

is the movement of particles across a membrane against a concentration gradient (i.e. from an area of lower to an area of higher concentration) using energy transferred during respiration.