Lifestyle & Risk

Question 1

What are the 4 bases in DNA?

Answer 1

Adenine,thymine,cytosine,guanine

Question 2

Which dna bases are purines and which are pyrimidines?

Answer 2

A,G = purines. T,C = pyrimidines

Question 3

What enzyme breaks the hydrogen bonds in dna replication?

Answer 3

DNA Helicase

Question 4

Describe the 3 steps of dna replication

Answer 4

1. DNA helicase unwinds and breaks hydrogen bonds exposing the bases and form 2 template stands
2. New dna is built up from the 4 nucleotides( A,C,G,T) that are abundant in the nucleoplasm,they then attach themselves to the bases on the old strands through complimentary base pairing
3. DNA polymerase joins new nucleotides to each other by strong covalent bonds forming the sugar-phosphate backbone then winding enzyme winds new strands up to form 2 double helixes creating 2 new identical molecules to the old singular molecule

Question 5

Describe experiment carried out by Meselson and Stahl demonstrates the semiconservative replication of DNA. Include an outline
of the method and a description of the results (5).

Answer 5

• Bacteria initially fed on N15/heavy N
• Bacteria then fed on N14/light N
• DNA extracted and separated (centrifugation) after 1 and 2 (and more) cell cycles
• DNA initially as a single band of heavy DNA (or diagram)
• DNA after 1 cycle of DNA replication as a single band of
intermediate DNA (or diagram)
• DNA after 2 cycles as one band of intermediate and one band of light DNA (or diagram)

Question 6

Define a monomer. Give examples

Answer 6

Smaller units that join together to form larger molecules

• monosaccharides(glucose,fructose,galactose)
• amino acids
  -nucleotides

Question 7

Define polymer.give some examples

Answer 7

Molecules formed when many monomers join together

• polysaccharides
• proteins
• DNA/RNA

Question 8

What happens in a condensation reaction

Answer 8

Chemical bond forms between 2 molecules and a molecule of water is produced

Question 9

What are disaccharides and polysaccharides and what bonds form these?

Answer 9

Disaccharides= 2 momomers joined together by 1 chemical bond

Polysaccharides= multiple monomers Joined by many chemical bonds

(1,4 or 1,6) glycosidic bond

Question 10

What are carbohydrates and what bond joins them together ?

Answer 10

Carbohydrates are molecules which consist only of carbon,hydrogen and oxygen and they’re long chains if sugar units called saccharides. A single monomer is called a monosaccharide ant glycosidic bonds can join them together to create disaccharides(2 molecules) and polysaccharides (many molecules)

Question 11

Give examples of monosaccharides,disaccharides and polysaccharides

Answer 11

Monosaccharides=
glucose(6 carbon atoms in each molecule,can be alpha or beta),fructose and galactose.

Disaccharides=
maltose(2 glucose molecules),
Sucrose(glucose & fructose) ,
Lactose(glucose & galactose)

Polysaccharides=
Glycogen( many alpha glucose)
Starch(many alpha glucose)
Cellulose(many beta glucose)

Question 12

What are lipids and what are the main lipid types?

Answer 12

Biological molecules made of carbon,hydrogen and oxygen

Main lipid types=
triglycerides( 1 mol of glucose and 3 fatty acids joined by ester bonds.can be saturated or unsaturated)

Phospholipids(one fatty acid substituted by a phosphate-containing group)

Question 13

What is the difference between saturated and unsaturated lipids?

Answer 13

Saturated-don’t contain any c-c double bonds,found in animal fats.

Unsaturated- DO contain c-c double bonds meaning they can bend,are liquid at room temp,found in plants.

Question 14

What are the different properties of triglycerides and phospholipids?

Answer 14

Triglycerides-
high ratio of energy storing C-H bonds to carbon atoms,excellent energy store),
Low mass to energy ratio(+ storage molecule), ‘

Question 15

What are the 2 key chemical reactions?

Answer 15

Condensation reaction- joining 2 molecules creating a chemical bond and removing water

Hydrolysis reaction- breaking of a chemical bond between 2 molecules involving the use of water

Question 16

Draw the structure of alpha glucose&beta glucose

Answer 16

Use pictures from notes to mark

Question 17

What is the formula for alpha glucose

Answer 17

Alpha- C6H12O6

BETA-

Question 18

What are proteins made up of?

Answer 18

Amino acid group(left), variable group (r),hydrogen and carboxyl group(right)

Question 19

What is RNA?

Answer 19

A polymer of a nucleotide formed of ribose,a nitrogenous base and a phosphate group.

Question 20

What is the function of RNA?

Answer 20

To transfer the genetic code from DNA in the nucleus to the ribosomes

Question 21

What are the 5 key properties of water?

Answer 21

1. It is a metabolite
   2.an important solvent in reactions
   3.has a high heat capacity, it buffers temp
   4.has strong cohesion between water molecules;supports water columns and provides surface tension

Question 22

Give Examples of cardiovascular disease

Answer 22

Coronary heart disease
Heart attacks
Faulty valves
Heart failure

Question 23

State and explain some treatments for coronary heart disease

Answer 23

Coronary heart disease-
Stents=expandable tube that can be placed inside coronary arteries to hold them open to ensure blood can keep flowing. Benefits = surgery is quick and can last a long time. Issues= surgery has risks,blood clot developing near stent .

Statins-
Medication that alters the balance of cholesterol in blood stream by ⬇️ amount of LDL(bad cholesterol) and ⬆️ amount of HDL(good chol). Cons of statins=taken regularly for years,side effects.

Question 24

Draw a labelled diagram of the heart

Answer 24

Use photos to mark and annotate.

Question 25

What is a null hypothesis

Answer 25

Hypothesis stating their is no difference between 2 means. If calculated answer is above degrees of freedom we reject the null hypothesis,if it is lower we accept the null hypothesis

Question 26

Why do mammals need a circulatory system

Answer 26

For adequate respiration ( intake of oxygen & glucose & disposal of co2 and Uria)

Question 27

Label the interior and exterior structure of the heart

Answer 27

Use unlabelled pic on Google then text book diagram on page 6 for marking

Question 28

Summarise the heart dissection

Answer 28

External examination: If you look at the outside of the heart you will see the four main vessels attached to it. The feel of the vessels can be used to help identify each one - arteries are thick and rubbery, whereas veins are much thinner
You will also be able to see the right and left atria, the right and left ventricles and the coronary arteries.

Internal examination: The ventricles can be cut open using a scalpel so you can see inside each one. You should be able to see that the wall of the left ventricle is thicker than the wall of the right ventricle.The atria can also be cut open. If you look at the atria walls, you should notice that they are thinner than the ventricle walls.
You can also look at the structures of the atrioventricular valves and semi-lunar valves.

Question 29

What are The different parts of the heart and their functions?

Answer 29

1) The left ventricle of the heart has thicker, more muscular walls than the right ventricle, because it needs to contract powerfully to pump blood all the way round the body. The right side only needs to get blood to the lungs, which are nearby.
2) The ventricles have thicker walls than the atria, because they have to push blood out of the heart whereas the atria just need to push blood a short distance into the ventricles.
3) The atrioventricular (AV) valves link the atria to the ventricles and stop blood flowing back into the atria when the ventricles contract. Cords attach the atrioventricular valves to the ventricles to stop them being forced up into the atria when the ventricles contract.
4) The semi-lunar (SL) valves link the ventricles to the pulmonary artery and aorta, and stop blood flowing back into the heart after the ventricles contract.

Question 30

How do valves help the blood flow in one direction?

Answer 30

The valves only open one way - whether they re open or closed depends on the relative pressure of the heart chambers.

If there’s higher pressure behind a valve, its forced open,but if pressure is higher in front of the valve its forced shut This means blood only flows in one direction through the heart.

Question 31

How do the arteries, capillaries and veins transport substances around the body?

Answer 31

1) Arteries carry blood from the heart to the rest of the body.
They’re thick-walled, muscular and have elastic tissue in the walls to cope with the high pressure caused by the heartbeat.
The inner lining (endothelium) is folded, allowing the artery to expand - this also helps it to cope with high pressure.

2) Veins take blood back to the heart. They’re wider than equivalent arteries, with very little elastic or muscle tissue as the blood is under lower pressure.
Veins contain valves to stop the blood flowing backwards. Blood flow through the veins is helped by contraction of the body muscles surrounding them.

3)Capillaries are the smallest of the blood vessels. They are where metabolic exchange occurs - substances are exchanged between cells and the capillaries.
There are networks of capillaries in tissue (called capillary beds), which increase the surface area for exchange. Capillary walls are only one cell thick, which speeds up diffusion of substances (e.g. glucose and oxygen) into and out of cells.

Question 32

What is the cardiac cycle?

Answer 32

The cardlac cycle is an ongoing sequence of contraction(systole) and relaxation (diastole) of the atria and ventricles that keeps blood continuously circulating round the body.the volume of the atria and ventricles changes as they contract and relax, Pressure changes also occur due to the changes in chamber volume (e.g decreasing the volume of the chamber by contraction will increase the pressure in the chamber)
The cardiac cycle can be simplified into three stages:
-Ventricular diastole, atrial systole
-Ventricular systole ,atrial diastole
-Cardiac diastole

Question 33

Explain the 3 stages of the cardiac cycle

Answer 33

1.Ventricular diastole, atrial systole
The ventricles are relaxed.The atria contract, decreasing the volume of the chambers and increasing the pressure inside the chambers. This pushes the blood into the ventricles. There’s a slight increase in ventricular pressure and chamber volume as the ventricles receive the ejected blood from the contracting atria.

2.Ventricular systole, atrial diastole
The atria relax. The ventricles contract, decreasing their volume and increasing their pressure. The pressure becomes higher in the ventricles than the atria, which forces the AV valves shut to prevent back-flow.The pressure in the ventricles is also higher than in the aorta and pulmonary artery, which forces open the SL valves and blood is forced out into these arteries.

3.Cardiac diastole
The ventricles and the atria both relax. The higher pressure in the pulmonary artery and aorta closes the Si valves to prevent back-flow into the ventricles. Blood returns to the heart and the atria fill again due to the higher pressure in the vena cava and pulmonary vein. In turn this starts to increase the pressure of the atria.
As the ventricles continue to relax, their pressure falls below the pressure of the atria and so the AV valves open. This allows blood to flow passively (without being pushed by atrial contraction) into the ventricles from the atria. The atria contract, and the whole process begins again.

Question 34

Annotate a cardiac cycle graph

Answer 34

Use unlabelled graph and then mark using graph in textbook page 9.

Question 35

What are calories

Answer 35

1 calorie (1 cal)
= the quantity of heat energy raise the temperature of 1g water by 1’c = 4.18 Joules (J)

1 Calorie (1 kcal) = 1000 cal = 4180 J = 4.18 kJ

Question 36

What are Dietary Reference Values (DRVs)?

Answer 36

energy and nutrient requirements for different groups of healthy people in the UK

Question 37

What is basal metabolic rate(bmr)?

Answer 37

= energy expended when completely at rest for
• heartbeat
• breathing
• body temperature

Question 38

Body mass index (BMI)

Answer 38

= a measure of body fat based on height and mass of adult men and women
BMI = body mass (kg) height2 (m2)