water/biomolecules

Question 1

what is an atom

Answer 1

A basic unit of matter that consists of a dense, central nucleus surrounded by a
cloud of negatively charged electrons.

Question 2

what is a molecule

Answer 2

An electrically neutral group of at least two atoms in a definite arrangement held
together by very strong (covalent) bonds

Question 3

what is a compound

Answer 3

A pure chemical substance consisting of two or more different chemical elements
that can be separated into simpler substances by chemical reactions.

Question 4

what is an element

Answer 4

A pure chemical substance consisting of one type of atom distinguished by its
atomic number, which is the number of protons in its nucleus

Question 5

what is an ion

Answer 5

A charged particle formed by the loss or gain of one or more electrons.

Question 6

what is an organic compound

Answer 6

one or more atoms of carbon are covalently linked to atoms of other elements

Question 7

what is an inorganic compound

Answer 7

Are considered to be of a mineral, not biological origin

Question 8

what is a polar molecule

Answer 8

has different charges across the molecule but overall is neutral

Question 9

what molecules can water dissolve

Answer 9

polar and ionic

Question 10

what is the structure of a water molecule

Answer 10

one slightly negative oxygen molecule and two slightly positive hydrogen molecules

Question 11

how do water molecules bond together

Answer 11

the slightly positive hydrogen attracts the slightly negative oxygen from another molecule

Question 12

how do you represent a hydrogen bond between two water molecules bonded together

Answer 12

with a dashed line

Question 13

why is water important in animals

Answer 13

-used to filter kidneys
-allows solutes to be transported and dissolved in blood plasma

Question 14

what is water important in plants

Answer 14

allows solutes to be transported and dissolved in water in xylem and phloem vessels

Question 15

what is cohesion

Answer 15

when water molecules stick together

Question 16

how do water molecules bond together

Answer 16

via a weak hydrogen bond (- - -)

Question 17

how does cohesion of water moelcules benefit animals

Answer 17

allows water surface tension which lets animals walk on water

Question 18

how does cohesion of water moelcules benefit plants

Answer 18

allows water to be pulled through xylem to top of plants

Question 19

how does specific heat capacity help animals

Answer 19

stabalises aquatic enviroment temps

Question 20

why does water have a high latent heat of vaporisation

Answer 20

can absorb large amounts of heat whe changing from liquid to vapour

Question 21

is ice or water less dense

Answer 21

ice

Question 22

why is ice less dense

Answer 22

ice particles from rigid structures so theres more space between so arent as many hydrogen bonds whereas water particles can get very close

Question 23

how does ice help animals

Answer 23

helps protect using the insulated layer

Question 24

why do living organisms need magnesium

Answer 24

makes chlorophyll in leaves
causes chlorosis if deficient
mamals need for bone density

Question 25

why do living organisms need iron

Answer 25

component of haemoglobin in red blood cells and used to transport oxygen
anemia if deficient

Question 26

why do living organisms need calcium

Answer 26

strengthening tissues bones and teeth in animals
cell walls in plants

Question 27

why do living organisms need phosphate

Answer 27

component of nucleic acids (DNA/RNA/ATP) and phospholipids

Question 28

how to test for starch

Answer 28

add dilute iodine
brown orange- blueblack

Question 29

how to test for glucose (reducing sugar)

Answer 29

benedicts reagents and heat gently (1 minute)
- brick red

Question 30

how to test for sucrose (non reducing sugar)

Answer 30

Add 1cm3 hydrochloric acid to the sample and boil
(to hydrolyse (break down) the sucrose into
glucose and fructose)
Neutralise the solution with an alkali.
Boil for one minute with Benedict’s solution.
-Blue to brick red

Question 31

how to test for lipids

Answer 31

emulsions test- add ethonal and shake with water
- white emulsion

Question 32

why do we use ethanol to test for lipids

Answer 32

ethonal dissolves any fats present and lipids arent insolubale in water so come out of solutions as emulsion

Question 33

how to test for protein

Answer 33

biurets test
add sodium hydroxide and copper sulphate
blue - purple

Question 34

what is the role of water as a metabolite

Answer 34

• a reactant in photosynthesis and hydrolysis
• a product of aerobic respiration and condensation reactions