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Biology > Topic 3 Chemicals of Life > Flashcards

Topic 3 Chemicals of Life Flashcards

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0
Q

3.1.2

Outside of the four main elements what other elements are needed by living organisms?

A 
Sulphur
Calcium
Phosphorus
Iron
Sodium
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1
Q

3.1.1

What are the most frequently occurring elements in living things?

A

Carbon (19%)
Hydrogen (10%)
Oxygen (65%)
Nitrogen (3%)

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2
Q

3.1.3

What is the role of sulphur in living organisms?

A

Found in certain amino acids (cysteine and methionine), allowing proteins to form disulphide bonds

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3
Q

3.1.3

What is the role of calcium in living organisms?

A

Found in bones and teeth, also involved in neurotransmitter release in synapses

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4
Q

3.1.3

What is the role of phosphorus in living organisms?

A

Component of nucleic acids and cell membranes

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5
Q

3.1.3

What is the role of iron in living organisms?

A

Found in haemoglobin (animals), allowing for oxygen transport

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6
Q

3.1.3

What is the role of sodium in living organisms?

A

Involved in the generation of nerve impulses in neurons

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7
Q

3.1.5

Outline the thermal properties of water

A
  • Water has a high specific heat capacity (the measure of energy required to raise the temperature of 1g of substance by 1 degree C)
  • Water has a high heat of fusion (amount of energy required to be lost to change 1g of liquid to 1g of solid at 0 degrees C)
  • These properties occur as a result of the extensive hydrogen bonding between water molecules - this allows water to absorb considerable amounts of energy with little change in (H-bonds need to be broken first)
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8
Q

3.1.5

Outline the cohesive properties of water

A

Water molecules are strongly cohesive
Water molecules will also tend to stick to other molecules that are charged or polar
These properties occur as a result of the polarity of water and its ability to form hydrogen bonds with appropriate molecules

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9
Q

3.1.5

Outline the solvent properties of water

A

Water can dissolve many organic and inorganic substances that contain electronegative atoms
This occurs because the polar attraction of large qualities of water molecules can sufficiently weaken intramolecular forces (e.g. Ionic bonds) and result in the dissociation of the atoms

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10
Q

3.1.6

Explain the relationship between the properties of water and it’s use in living organisms as a coolant.

A

Both plants and animals use the evaporation of water from the surfaces of their bodies to facilitate cooling (sweating and panting in animals, transpiration from leaves in plants)
Water can be used to carry heat to cooler places in our bodies

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11
Q

3.1.6
Explain the relationship between the properties of water and it’s use in living organisms as a medium for metabolic reactions

A

Water can dissolve many substances to facilitate chemical reactions
Water can also absorb thermal energy released as a byproduct of many chemical reactions

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12
Q

3.1.6

Explain the relationship between the properties of water and it’s use in living organisms as a transport medium

A

The forces of attraction between water molecules help facilitate the transport of water up the xylem of plants
Water is an effective transport of medium for dissolved substances

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13
Q

3.1.6

How can some small organisms ‘walk on water’

A

The force of attraction between water molecules makes waters sufficiently dense for some smaller organisms to move along its surface

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14
Q

3.2.1

Distinguish between organic and inorganic compounds

A

Organic compounds are compounds containing carbon found in living things, except hydrogen carbonates, carbonates and oxides of carbon
Inorganic compounds are all other compounds

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15
Q

What Are carbohydrates?

A

Organic compounds, consisting of one or more simple sugars that as monomers follow the general basic formula of (CH2 O)x

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16
Q

3.2.3

List three examples of a monosaccharide

A

Glucose, galactose, fructose

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17
Q

3.2.3

List three examples of a disaccharide:

A

Lactose, maltose, sucrose

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18
Q

3.2.3

List three examples of a polysaccharide

A

Cellulose, glycogen, starch

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19
Q

3.2.4

State one function of glucose, lactose and glycogen in animals

A

Glucose:
A source of energy which can be broken down to form ATP via cellular respiration

Lactose:
A sugar found in the milk of mammals, providing energy for suckling infants

Glycogen:
Used by animals for short term energy storage (between meals) in the liver

20
Q

3.2.4

Explain one function of fructose, sucrose and cellulose in plants.

A

Fructose:
Found in honey and onions, it is very sweet and a good source of energy

Sucrose:
Used primarily as a transportable energy form

Cellulose:
Used by plant cells as a strengthening component of the cell wall

21
Q

What is a lipid? Name three common lipids

A

A group of organic molecules that are insoluble in water but soluble in non-polar organic solvents

Triglycerides, phospholipids and steroids

22
Q 
3.2.6
State three (out of five) functions of lipids
A

Structure: phospholipids are a main component of cell membranes
Hormonal signalling: steroids are involved in hormonal signalling (e.g. Oestrogen, preogesterone, testosterone)
Insulation: fats in animals can serve as heat insulators while sphingolipids in the myelin sheath (of neurons) can serve as electrical insulators
Protection: triglycerides may form a tissue layer around many key internal organs and provide protection against physical injury
Storage of energy: triglycerides can be used as a long term energy storage source

23
Q

3.2.7

Compare the use of carbohydrates and lipids in energy storage

A

Similar:
Complex carbohydrates and lipids both contain a lot of chemical energy and can be used of energy storage.
Complex carbohydrates and lipids are both insoluble in water - they are not easily transported
Carbohydrates and lipids both burn cleaner that proteins

Differences:
Lipid molecules contain more energy per gram than carbohydrates
Carbohydrates are more readily digested that lipids and release their energy more rapidly
Monosaccharides and disaccharides are water soluble and easier to transport to and from storage sites than lipids
Animals tend to use carbohydrates primarily for short term energy storage, while lipids are used for more long term storage
Carbohydrates are stored as glycogen in animals, while lipids are stored as fats
Lipids have less effect on osmotic pressure within a cell than complex carbohydrates

24
Q

What are proteins?

A

Large organic compounds made of amino acids arranged in a linear chain

25
Q

3.3.2

What are the names of the four bases in DNA? How do they pair up?

A

Adenine & thymine

Guanine & cytosine

26
Q

3.4.1
Explain DNA replication in terms of unwinding of the double helix and separation of the strands by helicase, followed by the formation of the new complementary strands by DNA polymerase

A

Helicase:
Unwinds the DNA and separates the two polynucleotide strands by breaking the hydrogen bonds between complementary base pairs
The two separated polynucleotide strands act as templates for the synthesis of new polynucleotide strands

DNA polymerase:
Synthesis new strands from the two parental template strands
Free deoxynucleoside triphosphates are aligned opposite their complementary base partner are covalently bonded together by DNA polymerase to form a complementary nucleotide chain
The energy for this reaction comes from the cleavage of the two extra phosphate groups

27
Q

3.4.2

Explain the significance of complementary base paring in the conversation of the base sequence of DNA

A

Each of the nitrogenous bases can only pair with its complementary partner (a=t, g=c)
Consequently, when DNA is replicated by the combined action of helicase and DNA polymerase:
The new strands formed will be identical to the original strands separated from the template
The two DNA molecules formed will be identical to the original molecule

28
Q

3.4.3

How is DNA replication semi-conservative?

A

Because when a new double strand DNA molecule is formed:
One strand will be from the original molecule
One strand will be newly synthesised

29
Q

3.5.1

Compare the structure of DNA and RNA

A

DNA has the sugar deoxyribose, RNA has the sugar ribose.
DNA has the base thymine, and RNA has uracil.
DNA is double stranded and RNA is usually single stranded.
DNA forms a double helix and RNA does not

30
Q

3.6.1

Define enzyme

A

A globular protein that increases the rate of a biochemical reaction by lowering the activation energy threshold

31
Q

3.6.1

Define active site

A

The site on the surface of an enzyme which binds to the substrate molecule

32
Q

3.6.2

Explain enzyme substrate specificity

A

Active site and substrate complement each other in terms of both shape and chemical qualities (e.g opposite charges)
Binding to the active site brings the substrate into close physical proximity, creating an enzyme substrate complex
The enzyme catalyses the conversion of the substrate into a product(s) creating an enzyme product complex
As the enzyme is not consumed in the reaction it can continue to work once the product dissociates

33
Q

3.6.3

Explain the effects of temperature on enzyme activity

A

Low temperatures result in insufficient thermal energy for the activation of a given enzyme-catalysed reaction to be achieved
Increasing the temperature increases the speed and motion of enzyme and substrate –> higher enzyme activity, higher kinetic energy results in mor frequent collisions between enzyme and substrate.
At optimal temperature the rate of enzyme activity will be at its peak
Higher temperatures can cause enzymes to denature

34
Q

3.6.3

Explain the effects of pH on enzyme activity

A

Changing the pH will alter after the charge of the enzymes which in turn will protein solubility and may change the shape of the molecule
Changing the shape of the active site will diminish it’s ability to bind to the substrate
Enzymes have an optimum pH and moving outside of this range will result in a diminished rate of reaction

35
Q

3.6.3

Explain how substrate concentration effects enzyme activity

A

Increasing substrate concentration will increase the activity of a
particular enzyme.
More substrate means there is an increased likelihood of enzyme substrate collisions and reactions
After a certain point the rate of reaction will cease to rise as the environment would becoMe saturated and all enzymes are bound and reacting

36
Q

3.6.4

Define denaturation

A

Structural change in a protein that results in the loss (usually permenant) of its biological properties
Can be caused by heat or pH

37
Q

3.7.1

Define cell respiration

A

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

38
Q

3.7.2

What happens to glucose in the cytoplasm during cell respiration?

A

Glycolysis - the breakdowns of one molecule of glucose (6C) into two molecules of pyruvate (2 * 3C) with a small net yield of ATP (2 molecules of ATP)
This process also results in the reduction of two hydrogen acceptors to form two molecules of NADH + H+

39
Q

3.8.1

What is photosynthesis? Outline the two stages.

A

The process by which plants synthesise organic compounds in the presence of sunlight.

1) the light dependant reactions convert the light energy into chemical energy (ATP)
2) the light dependant reactions use the chemical energy to synthesised organic compounds
The organic molecules produced in photosynthesis can be used in cellular respiration to provide the energy needed by the organism

40
Q

3.8.2

What colours is sunlight made up of?

A 
Red
Orange
Yellow
Green
Blue
Indigo
Violet
41
Q

3.8.3

What is chlorophyll?

A

The main site of light absorption in the light dependant stage of photosynthesis
There are a number of different chlorophyll molecules, each with their own distinct absorption spectra
The main photosynthetic pigment, that absorbs light energy and release electrons which are used to make ATP.

42
Q

3.8.4

Outline the difference in absorption of red, green and blue light by chlorophyll

A

The main colours of light absorbed by chlorophyll are red and blue light
Main colour not absorbed is green (it’s reflected)
Explains why leaves are green. Excepting when the prescience of other pigmented substances produces a different colour

43
Q

3.8.7

How can you measure carbon dioxide uptake in photosynthesis?

A

CO2 uptake can be measured by placing a plant in an enclosed space with water
Carbon dioxide interacts with the water molecules, producing bicarbonate and hydrogen ions, which increases the acidity of the resulting solution
The change in pH can therefore provide a measure of CO2 uptake by a plant

44
Q

3.8.7

How can you measure oxygen production at different rages of photosynthesis?

A

Oxygen production can be measured by submerging a plant in an enclosed space with water attracted to a sealed gas syringe

An oxygen gas produced will bubble out of solution and can be measured by a change in water level

45
Q

3.8.7

How can the rate of photosynthesis be measured indirectly by an increase in biomass?

A

Glucose production can be indirectly measured by a change in the plant’s biomass.
This requires the plant to be completely dehydrated prior to the weighing to ensure the change in biomass reflects a change in organic matter not water content
Or to determine the change in starch levels in a plant, starch can be identified by iodine staining and quantitated using a colorimeter

46
Q

3.8.8

Outline the effect of temperature of the rate of photosynthesis

A

Photosynthesis is controlled by enzymes which are sensitive to temperature
As temperature increases the rate of photosynthesis will increase as reagents have greater kinetic energy and are more likely to react.
above a certain temperature, the rate of photosynthesis will decrease as essential enzymes begin to denature

47
Q

3.8.8

Explain how light intensity affects photosynthesis

A

As light intensity increases the rate of photosynthesis will increase up until a certain point, when photosynthesis is proceeding at its maximum rate
Further increases to light intensity will have no effect on photosynthesis as chlorophyll at saturated by light
Different wave lengths of light will have different effects on rate of photosynthesis

48
Q

3.8.8
Outline the effect of carbon dioxide concentration on the rate of
Photosynthesis

A

As the concentration of carbon dioxide increases, the rate of photosynthesis will increase up until a certain point, when photosynthesis is proceeding at its maximum rate
Further increases to carbon dioxide concentration will have no effect on photosynthesis, as the enzymes responsible for carbon fixation become saturated

Biology (5 decks)

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