Topic 3 Chemistry Of Life

Question 0

What is a hydrogen bond?

Answer 0

When a Bond forms between the positive and negative pole of water molecules. In liquid water, these bonds are formed making it a very useful substance for living organisms.

Question 1

What is polarity?

Answer 1

When a molecules have two poles, e.g. Water has a positive hydrogen pole and negative oxygen pole.

Question 2

Name the properties of water.

Answer 2

Cohesion, solvent properties, thermal properties: heat capacity, boiling point, the cooling effect of evaporation.

Question 3

What are the essential elements needed by a living organism?

Answer 3

Carbon, nitrogen, hydrogen, oxygen.

Question 4

What more elements are needed by a living organism?

Answer 4

Calcium, sulfur, iron, phosphorus, iron.

Question 5

Outline the properties of water and explain the relationship between it and it’s uses in living organisms: cohesion.

Answer 5

Water molecules stick to each other because of the hydrogen bonds that are formed between them. This is important because strong pulling forces are exerted to suck columns of water up to the tops of trees in their transport system. The columns of water brisk rarely. The water is used as a transport medium in the xylem of plants.

Question 6

Outline the properties of water and explain the relationship between it and it’s uses in living organisms: solvent properties.

Answer 6

Many different substances can dissolve into water due to their polarity. Inorganic particles with positive or negative charges will dissolve, such as sodium ions. Organic substances with polar molecules will also dissolve. Enzymes can also dissolve in water.

This property is important because most chemical reactions take place with all of the substances involved in the reactions dissolved with water. Water is the medium for metabolic reactions. The solvent property also allows many substances to be carried dissolved in water in the blood of animals and sap of plants. Therefore it can be used as a transport medium.

Question 7

Outline the properties of water and explain the relationship between it and it’s uses in living organisms: heat capacity

Answer 7

Water having a large heat capacity means that a large amount of energy is needed in raising the temperature of it. This is because of the hydrogen bonds.

This is useful because blood which is mainly composed of water can carry heat from warmer parts of the body to cooler parts. Blood is used as a transfer medium of heat.

Question 8

Outline the properties of water and explain the relationship between it and it’s uses in living organisms: cooling effect of evaporation.

Answer 8

Water can evaporate below the boiling to point. In order for this to happen the hydrogen bonds need to be broken. The heat needed to do this is taken from liquid water, which cools it down.

This is essential because evaporation of water from plants, known as transpiration and from human skin, known as sweating, has useful cooling effects. Water is used as a coolant.

Question 9

Outline the properties of water and explain the relationship between it and it’s uses in living organisms: boiling point.

Answer 9

The boiling point of water is very high, because all H-bonds need to be broken in order to for it to go to a gaseous state.

This is important because as a liquid, water can act as a medium for metabolic reactions. In most places on earth, water is below BP mad above MP.

Question 10

What is the role of sulphur?

Answer 10

It is needed to make two of the twenty amino acids in proteins.

(For synthesis of amino acids)

Question 11

What is the use of calcium?

Answer 11

Acts as a messenger, binding to calmodulin and other proteins that regulate processes inside cells, including transcription.

Question 12

What is the use of phosphorus?

Answer 12

To art of phosphate groups in ATP and DNA molecules.

Question 13

What is the use of iron?

Answer 13

It is needed to make cytochromes - proteins used for electron transport during aerobic cell respiration.

Question 14

What is the use of sodium?

Answer 14

Pumped into the cytoplasm to increase solute concentration , which leads to the water entering by osmosis.

Question 15

Name inorganic carbon compounds.

Answer 15

Carbon dioxide, hydrogen carbonates, carbonates.

Question 16

What are organic compounds?

Answer 16

Company da containing carbon and that are in living organisms.

Question 17

What are inorganic compounds?

Answer 17

Compounds that contain no carbon.

Question 18

What are the three largest organic compounds found in living organisms?

Answer 18

Lipids, proteins and carbohydrates.

Question 19

What are the three functions of lipids?

Answer 19

Heat insulation - layer of fat beneath the skin, reduces heat loss

Buoyancy - lipids are less dense than water, therefore let animals float.

Energy storage - in the form of fat in humans and oils in plants

Question 20

Three examples of mono, di and polysaccharides.

Answer 20

Mono - glucose, galactose, fructose
Di - lactose, maltose, sucrose
Poly - cellulose, glycogen, starch

Question 21

Functions of the saccharides for animals and plants.

Answer 21

Glucose - blood carries it to transports energy to cells throughout the body
Fructose - used to make fruits sweet smelling, so that they attract animals and then seed is dispersed In the fruit
Lactose - sugar in the milk which provides energy to young mammals unti, they are weaned.
Sucrose - carried by the phloem throughout the plant to transport energy to the cells
Cellulose - used to make strong fibers for the construction of cell walls of plant cells
Glycogen - short term energy storage in the lover and muscles

Question 22

Explain the condensation reaction processes

Answer 22

Two amino acids and condensed together to for di peptide and water, this same process continues to the making polypeptides.

Monosaccharides to disaccharides to polysaccharides. And water.

Fatty acid and glycerol to make a glyceride and water. Max of three fatty acids can be linked to each glycerol to form triglyceride.

Question 23

Compare the use of carbs and lipids as energy storage.

Answer 23

Lipids contain more energy per gram compared to carbs therefore stores of lipids are lighter than stores of carbs that contain the same amount of energy.
They are also insoluble in water therefore do not interfere with osmosis in cells. They are long term storage.

Carbs are more easily digested than lipids so the energy stored by them can be released More rapidly. They are soluble in water so they are easier to transport to and from the store. Carbs are short term storage.

Question 24

What are the names of the nucleotide bases?

Answer 24

Adenine, guanine, cytosine and thymine

Question 25

Outline the structure of a DNA nucleotide.

Answer 25

Phosphate (circle)

Deoxyribose (sugar pentagon shape) and a nitrogenous base.

Question 26

What affects enzyme activity?

Answer 26

Temperature, ph and substrate concentration.

Question 27

State the effect of temperature on enzyme activity.

Answer 27

It increases as temperature increases, often doubling with every 10 degree rise. This is because collisions between substrates and enzymes happen more frequently at higher temperatures due to faster molecular motion. However, at a high temperature, the enzyme denatures, due to breaking of the bonds needed to maintain the structure of the enzyme.

Question 28

How does ph affect the enzyme activity.

Answer 28

The optimum ph is 7. However, as ph increases or decreases, the enzyme activity decreases as it affects the structure of the binding site and the substrate cannot fit in too well. Therefore, enzymes get denatured and cannot catalyze.

Question 29

State the effect of substrate concentration on enzyme activity.

Answer 29

When concentration is increased during low concentration, the activity increases steeply, because random collisions between substrate and active site happen more frequently at higher substrate concentration. However at high concentration, the raising of concentration does not affect much as most active sites are occupied.

Question 30

Explain the use of lactase in the production of lactose free milk.

Answer 30

Lactose converts into glucose and galactose by the enzyme lactase.

Lactase is obtained from kluveromyces lactis, a type of Yeast that grows naturally in milk. The Yeast is cultured, then the lactase extracted and purifies and sold on to manufacturing companies.

Lactose free milk is made, for lactose intolerant people. They cannot drink more than 250ml of milk per day otherwise. Their bodies do not produce lactase enzyme therefore they cannot be broken down.

Glucose and galactose are sweeter than lactose, so this can be used to add less shaver tossed foods containing milk.

Lactose crystallizes during production of ice cream, giving a gritty texture, glucose and galactose are more soluble and therefore they remain dissolved and give a smooth texture,

Bacteria ferment glucose and galactose more quickly , therefore production of cottage cheese and yoghurt happen faster.

The lactase can be added to milk, so that the final product contains the enzyme.

It can be immobilized on a surface or beads of a porous material. The milks is allowed to flow past the immobilized lactase. This avoids the contamination of the product with lactase.

Question 31

Define cell respiration.

Answer 31

Controlled release of energy from organic compounds in cells to form ATP.

Question 32

Explain the use of glucose in cell respiration.

Answer 32

Glucose is the organic compound in cell respiration. Chemical reactions In the cytoplasm break down glucose into a simpler organic compound called pyruvate. In this reaction, a small amount of ATP is made using energy released from glucose.

Question 33

How can rate of photosynthesis be measured?

Answer 33

Production of oxygen. Aquatic plants produce bubbles of oxygen. If they can be collected, their volume can be measured.

Uptake of carbon dioxide. Leaves take in co2 from the air or water around them. This is hard to measure directly. If co2 is absorbed from water, the ph level of water rises. This can be measured using ph Meters or indicators.

And increase in biomass. If batches of plants are harvested at a series of times and the biomass of the batches determines, the rate of increase in biomass gives an indirect measure of the rate of photosynthesis in the plants.

Question 34

State the effect of co2 on photosynthesis.

Answer 34

There is no photosynthesis at low CO2 concentration. As it increases from low to high, the rate of photosynthesis increases, it is positively correlated. However, at a very high CO2 concentration, the rate reaches a plateau.

Question 35

State the effect of light intensity in photosynthesis.

Answer 35

At low to medium light intensities the rate of photosynthesis is directly proportional to light intensity. However at high intensities, a palette a is reached.

Question 36

State the effect of temperature on photosynthesis.

Answer 36

As temperature is increased, the rate increases more and more steeply until it reaches optimum temperature. After that, when temperature is increased, the rate falls steeply.