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Bio A-level > Bio Molecules > Flashcards

Bio Molecules Flashcards

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1
Q

Compare and contrast the structure AND properties of triglycerides and phospholipids

A

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

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2
Q

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

A

Glucose and galactose monosaccharides

joined by a condensation reaction

joined by a glycosidic bond
Added to polypeptide in Golgi apparatus

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3
Q

Give properties of water that are important to biology

A

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

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4
Q

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

A
  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
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5
Q

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

A

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

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6
Q

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

A

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

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7
Q

Explain the importance of the hydrolysis of ATP

A

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

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8
Q

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

A
  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
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9
Q

an arteriole is describes as an organ. Explain why

A

it is made up of different tissues

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10
Q

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

A

muscles contract

arteriole constricts.

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11
Q

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

A
  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
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12
Q

translation

A

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

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13
Q

transcription

A
  • 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
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14
Q

give ways starch is similar to cellulose

A
  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
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15
Q

gives starch is different to cellulose

A
  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
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16
Q

contrast the processes of facilitated diffusion and active transport

A
  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
17
Q

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

A
  • loss of elasticity, as elastic tissue becomes scar tissue
  • there is less recoil
    (recoil helps create a pressure gradient for expiration)
18
Q

describe and explain the differences between the two curves

A
  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
19
Q

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

A
  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
20
Q

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)

A

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 :

  1. 31 - 0.14 =
  2. 17 g dm-3 year-1
21
Q

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)

A

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;

22
Q

what does rate of diffusion depend on?

A
  • the surface area to volume ratio
  • the diffusion distance (thickness of diffusion surface
  • differences in concentration (how steep conc.grad is)
23
Q

why is the bilayer called fluid?

A

because phospholipids are constantly moving

24
Q

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

A

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

25
Q

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?

A

promoter region/gene

26
Q

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

A
  1. so proteins can be harvested

2. Fibres in other cells may cause harm

27
Q

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

A

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

28
Q

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

A

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

29
Q

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

A

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)

30
Q

how is water being a solvent beneficial to the body?

A 
it readily dissolves substances : 
gases 
waste 
inorganic ions 
enzymes 
hydrophilic molecules
31
Q

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

A

along a diffusion gradient

mass transport

the ends of the tracheoles filled with water

32
Q

along diffusion gradient

A

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

33
Q

mass transport

A

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

34
Q

the ends of the tracheoles are filled with water

A

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

Bio A-level (10 decks)

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