Bio Molecules

Question 1

Compare and contrast the structure AND properties of triglycerides and phospholipids

Answer 1

Both contain ester bonds between glycerol and fatty acids

Both contain glycerol

Fatty acids on both may be saturated or unsaturated

Both contain C , H and O but phospholipids also contain P

Triglycerides have 3 fatty acids and phospholipids have 2 fatty acids + a phosphate group

Triglycerides are hydrophobic/non polar
And phospholipids have a hydrophilic and hydrophobic region

Phospholipids form a bilateral in water,
Triglycerides don’t

Question 2

Describe how lactose is formed and where in the cell it would be attached to a polypeptide to form a glycoprotein

Answer 2

Glucose and galactose monosaccharides

joined by a condensation reaction

joined by a glycosidic bond
Added to polypeptide in Golgi apparatus

Question 3

Give properties of water that are important to biology

Answer 3

Is a metabolite

Is a solvent

Has a relatively high heat capacity

Has a relatively large latent heat of vaporisation

Has cohesion/ H bonds between molecules

Question 4

Explain how a change in the sequence of DNA bases could result in a non functional enzyme (3)

Answer 4

1. Change in a sequence of amino acids/ primary structure
2. (Which) alters tertiary structure, active site of the enzyme
3. No enzyme substrate complexes are formed

Question 5

Hydrogen bonds occur between water molecules. Explain how these affect the properties of water as a habitat for organisms

Answer 5

hydrogen bonds:

make the temperature more STABLE / less likely to get too hot or too cold

make water less likely to evaporate (high latent heat of vaporisation

extra H bonds on freezing make ice float, insulates water below / provides new habitat

provides medium for gametes to travel

Question 6

Give 4 inorganic ions within the human body and describe one function of each

Answer 6

H+ affects pH / enhances pepsin action in stomach

Fe2+/3+ binds oxygen in haemoglobin

Na+ co transports with glucose and amino acids into cells

PO43- part of the structure of DNA/RNA/nucleotides like ATP

Question 7

Explain the importance of the hydrolysis of ATP

Answer 7

yields energy for metabolic reactions
short term energy currency in the cell
coupled to energy requiring reactions in the cell

Question 8

Describe and explain how fish maintain flow off water over their gills. (4)

Answer 8

1. mouth opens, opercular valves shut ]
2. Buccal floor of mouth lowered
3. water enters due to decreased pressure
4. mouth closes, opercular valves open
5. Buccal floor raised results in increased pressure
6. Increased pressure forces water over the gills

Question 9

an arteriole is describes as an organ. Explain why

Answer 9

it is made up of different tissues

Question 10

an arteriole contains muscle fibres, Explain how these muscle fibres reduce blood flow to the capillaries

Answer 10

muscles contract

arteriole constricts.

Question 11

explain why lack of protein in the blood causes a build up of tissue fluid

Answer 11

1. water potential in capillary is higher
   2 so less water moves in to capillary
2. by osmosis
3. so more tissue fluid builds up outside of capillary

Question 12

translation

Answer 12

happens in the cytoplasm
mRNA attaches to the ribosomes
a tRNA then attaches with a complementary anticodon to the codon on mRNA (the tRNA has an amino acid attached to it)
the ribosome moves along the mRNA, taking the tRNA with it
As tRN reaches the stop codon on the and detaches from the tRNA

Question 13

transcription

Answer 13

• DNA HELICASE
  breaks
• HYDROGEN BONDS between DNA strands
• only one DNA strand acts as a TEMPLATE
• RNA nucleotides attracted to exposed bases
  RNA polymerase joins complementary RNA nucleotides together
  Pre-mRNA spliced to remove introns

Question 14

give ways starch is similar to cellulose

Answer 14

1. contain glucose
2. contain carbon , hydrogen and oxygen
3. are polymers / are polysaccharides / are made of monosaccharides
4. contain glycosidic bonds
5. Hydrogen bonding

Question 15

gives starch is different to cellulose

Answer 15

1. Contains alpha glucose
2. Helical / coiled / branched
3. 1,6 glycosidic bonds (cellulose has 1,4)
4. glucose monomers are all the same way up

Question 16

contrast the processes of facilitated diffusion and active transport

Answer 16

1. facilitated diffusion involves channel or carrier proteins, whereas active transport only involves carrier proteins
2. facilitated diffusion does not use ATP and active transport does
3. Facilitated diffusion takes place down the gradient whereas active transport occurs against the concentration gradient

Question 17

people who have been fire breathers for main years often find they cannot breath out properly. Explain why.

Answer 17

• loss of elasticity, as elastic tissue becomes scar tissue
• there is less recoil
  (recoil helps create a pressure gradient for expiration)

Question 18

describe and explain the differences between the two curves

Answer 18

1. The initial rate of reaction is faster at 37 °C, indicated by the steeped curve;
2. Because more kinetic energy
3. So more E-S complexes formed/ so more E-S collisions
4. Graph plateaus at 37 °C;
5. Because all substrate is used up

Question 19

the graph shows the oxyhaemoglobin dissociation curves for two different species, a human, A, and a rat, B

Species B, the rat is more active than species A, the human. Use the graph to explain how the haemoglobin of the rats allow greater level of activity

Answer 19

1. the curve is further to right, indicating the Hb has a lower affinity for oxygen
2. therefore, haemoglobin unloads / dissociates more readily
3. more oxygen is delivered to cells/tissues/muscles
4. For greater/more/faster respiration

Question 20

the graph below shows the results of an investigation into the concentration of proteins in blood plasma for people between the ages of 60 and 95. The bars show +-1 standard deviation.

Using the graph, what is the difference between the rate of change of the mean concentration of protein in the blood plasma in males and females between the ages of 60 and 95. Show your working. (2)

Answer 20

rate = product ÷ time

rate of change of mean concentration of proteins in the blood plasma =

FEMALES 
difference in conc 
71 - 60 = 11 
over 35 years (95-60)
 11÷35= 0.31

MALES
difference in conc
69-64=5
5÷35=0.14

difference between rates in males and females :

0. 31 - 0.14 =
1. 17 g dm-3 year-1

Question 21

the graph below shows the results of an investigation into the concentration of proteins in blood plasma for people between the ages of 60 and 95. The bars show +-1 standard deviation.

A student concluded from the graph that the protein content of the blood plasma decreased with age more in females. Do you agree? (2)

Answer 21

Yes, the decrease is 11 in females and only 5 in females

However the difference is only significant at 95 years because the SNs do not overlap

OR

Differences in mean are not significant because 2 x SD would overlap;

Question 22

what does rate of diffusion depend on?

Answer 22

• the surface area to volume ratio
• the diffusion distance (thickness of diffusion surface
• differences in concentration (how steep conc.grad is)

Question 23

why is the bilayer called fluid?

Answer 23

because phospholipids are constantly moving

Question 24

suggest why the plasmids were injected into the eggs of silkworms rather than into silkworms.

Answer 24

genes will get into most cells of the silkworms (eggs)

Question 25

what would the scientists have inserted into the plasmid along with the spider gene to ensure the spired gene was only expressed in the silk glands of the silkworms?

Answer 25

promoter region/gene

Question 26

suggest two reasons why it was important that the spider gene was expressed only in the silk glands of the silkworms

Answer 26

1. so proteins can be harvested | 2. Fibres in other cells may cause harm

Question 27

describe the role of micelles in the absorption of fats into the cell lining of the illeum

Answer 27

micelles include bile salts and fatty acids make fatty acids more soluble in water release fatty acids to the cell maintain higher concentration of fatty acids to cell fatty acids absorbed by diffusion

Question 28

Describe the processes involved in the absorption and transport of digested lipid molecules from the ileum into the lymph vessels

Answer 28

micelles contain bile salts and fatty acids/ monoglycerides make fatty acids more soluble in water bring fatty acids/ monoglycerides to cells lining of the ileum fatty acids absorbed into the cell by diffusion triglycerides reform in cells (chylomicron) (created by golgi) vesicles move to cell membrane

Question 29

Describe how the structure of a protein depends on the amino acids it contains

Answer 29

Structure is determined by relative position of R group primary structure is sequence of amino acids secondary structure formed by hydrogen bonds between Amino acids tertiary structure formed by interactions (between R groups) creates active site in enzymes Quaternary structure formed by bonds between polypeptides (more than one polypeptide chain)

Question 30

how is water being a solvent beneficial to the body?

Answer 30

``` it readily dissolves substances : gases waste inorganic ions enzymes hydrophilic molecules ```

Question 31

give three ways respiratory gases move in and out of the tracheal system

Answer 31

along a diffusion gradient mass transport the ends of the tracheoles filled with water

Question 32

along diffusion gradient

Answer 32

respiration lower oxygen concentration towards ends of tracheoles falls this creates a diffusion gradient causes O2 to diffusion from atmosphere along the trachea to tracheoles to cells CO2 produced by the cells in respiration creates a diffusion gradient in the opposite direction to O2 this causes CO2 to diffuse along from the cells to tracheoles to tracheas to the atmosphere diffusion in air more rapid than water = respiratory gases exchanged quickly by this method

Question 33

mass transport

Answer 33

muscles in insects around tracheoles contract can squeeze the tracheae increasing the pressure enabling mass movements of air (forced out) out, vice versa speeds up the exchange of respiratory gases

Question 34

the ends of the tracheoles are filled with water

Answer 34

muscle cells around tracheoles anaerobically respire this produces lactate this is soluble lowers the water potential in the muscle cells so water moves into cells at the ends of tracheoles tracheoles decrease in volume, and so draw air further into them so final diffusion pathway is in gas rather than liquid phase (which is faster