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Biology Mocks january > Paper 1 > Flashcards

Paper 1 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

What is heamoglobins structure?

A
  • It is a protein with a quaternary structure
  • made up of 4 polypeptide chains each with a heam group containing Fe2+
  • each heam group binds to 1 O2 molecule
  • one heamoglobin molecule binds to 4 oxygen molecules.
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2
Q

What is association and dissociation?

A

Association- loading of oxygen

Dissociation- unloading of oxygen

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3
Q

What does affinity mean and what is high and low affinity?

A

High affinity for oxygen means it easily associates with oxygen but more difficult to dissociate and having a low affinity means it is hard to associate but easy to dissociate from oxygen.

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4
Q

What must heamoglobin do to be efficient?

A

To be efficient it must readily associate with oxygen at gas exchange sites and readily dissociate at respiring tissues

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5
Q

Why is heamoglobin able to fulfil its role?

A

It’s shape changes in presence of co2 so in high conc of co2 binding to oxygen becomes weaker so easier to dissociate delivering oxygen efficiently to respiring tissues.

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6
Q

Why do heamoglobins in different species have different affinity to oxygen?

A

They have different shape due to having different primary structure of amino acids and therefore different tertiary and quaternary structures resulting in a different shape which has different binding properties.

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7
Q

What factors affect heamoglobin function?

A
  • oxygen conc
  • CO2 conc basically due to PH changes
  • The molecules shape determines by primary structure etc
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8
Q

Explain the shape of the oxygen dissociation curve

A
  • shape of the heamoglobin molecule makes binding to the first o2 difficult
  • low o2 conc = low affinity to oxygen
  • after binding to first o2 quaternary structure changes making it easier to bind to the next
  • only small kpa increase is needed to encourage next o2 to bind = positive cooperativity
  • after binding to the 3rd the 4th is harder due to probability
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9
Q

What does the position of the oxygen dissociation curve mean?

A
  • shifted to the left = greater affinity of heamoglobin to oxygen
  • shifted right = lower affinity if heamoglobin to oxygen
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10
Q

What does CO2 do to heamoglobin and how does this help it fulfil its role?

A

Heamoglobin has a reduced affinity to oxygen in the presence of CO2

  • has exchange surface= low co2 = high affinity
  • high respiring tissues = high co3 = low affinity
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11
Q

What is an antibody?

A

It is a protein with specific binding sites which bind to specific antigens leading to their destruction.

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12
Q

Describe the structure of an antibody?

A

-They are proteins made up of 4 polypeptide chains
-They have 2 heavy chains and 2 light chains
-a variable region and a constant region
-

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13
Q

How does an antibody lead to destruction of antigens?

A

By agglutination or by acting as markers which alert the phagocytise cells so they can be engulfed and destroyed

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14
Q

Why is the difference between a eukaryote and prokaryote cell?

A

Eukaryote cells have a distinct nucleus and membraine bound organelles

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15
Q

What’s the structure and function of the CSM?

A
  • phospholipid bilayer

- controls the entry and exit into and out the cell

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16
Q

What’s the structure and function of the nucleus?

A
  • contains the nuclolus, a nuclear envelope and nucleoplasm

- it stores the DNA for the cell and the nuclear pores allow mRNA and ribosomes in

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17
Q

What’s the structure and function of mitochondria?

A
  • matrix, cristae, outer and inner membraine

- carry out aerobic respiration forming ATP

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18
Q

What’s the structure and function of the chloroplast?

A

Contains granna which are made up of stacks of up to 100 thylakoids which contain chlorophyll - there is also the stroma

They are the site of photosynthesis

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19
Q

What’s the structure and function on the Golgi apparatus ?

A
  • consists of a stack of membraine making up folded stacks called cisternae
  • they modify proteins, produce enzymes and lysosomes
  • transport molecules around the cell
20
Q

What’s the structure and function of lysosomes?

A

Formed from vesicles from the Golgi containing enzymes

They have digestive enzymes which breakdown pathogens and old organelles and food molecules

21
Q

What is the structure and function of the RER and the SER?

A

RER- has lots of ribosomes and rough looking , has a large surface area for protein synthesis

SER- smooth and tubular, they synthesise, store and transport lipids and carbohydrates

22
Q

Cell wall and vacuole (plant) structure and function?

A

Cell wall provides support and mechanical strength

The vacuole maintains cell structure and acts as a temp energy store

23
Q

Describe the gross structure of the human gas exchange system?

A

-Trachea- Bronchus -Bronchioles- The alveoli

24
Q

What are the alveoli?

A

Minute sacs where gas exchange takes place

25
Q

Describe the features of the alveoli and what makes the efficient?

A
  • They have their epithelial cell walls and collagen and elastic fibres in between to allow expansion and recoiling when expelling air
  • They have short diffusion pathway as the capillaries are thin walls and the blood vessels slow down and flatten as they pass through for efficient gas exchange
  • large surface area and the constant circulation and breathing allows a steep conc gradient to be established
26
Q

What is the mechanism of inspiration?

A
  • Internal intercostals relax, external contract
  • Ribs move up and out increasing thoracic volume
  • Diapharm contracts and flattens
  • increased volume = reduced lung pressure
  • Atmospheric pressure greater than lunch pressure so air forced into lungs
27
Q

Describe the mechanism of expiration?

A

-Internal intercostals contract and the external relax
—Ribs move down and I wards decreasing the thoracic volume
- Diaphram relaxes and therefore pushes up
- Decreased thorax volume results in increased pressure
- pulmonary pressure greater than atmospheric so air forced out

28
Q

What is DNA made up of and what are the bases?

A

DNA- contains a Deoxyribose sugar(pentose) ,a phosphate base, and a nitrogenous base
The bases are adenine guanine cystosine and thymine.
A+ T G+C always together in complementary base pairing

29
Q

What is the structure of DNA?

A

DNA is a double helix of two polypeptide chains joined by the hydrogen bonding between complimentary base pairs and the phosphodiester back bone (condensation reactions form this)
A+T form 2 hydrogen bonds where as G+C form 3

30
Q

Describe the process of DNA replication?

A

Semi- conservative :

  1. Double helix unwinds the enzyme DNA helicase breaks the hydrogen bonds
  2. This results in two separate DNA strands the exposed polynucleotide chain acts as a template for free nucleotides to join
  3. Nucleotides join by condensation reactions by the enzyme DNA polymerase
  4. Each new DNA molecule contains one strand of original and one new DNA
31
Q

What is translocation?

A

Movement of organic substances from source (where they are made e.g photosynthesising cells) to sink (where they are used)

32
Q

Explain the process of translocation?

A
  1. Sucrose moves down a conc gradient by facilitated diffusion from photosynthesising cells into companion cells - H+ ions are actively transported into the cell wall
  2. Sucrose and H+ ions move into the sieve tube by co transport
  3. Sieve tube has lower water potential so water moves into sieve tube by osmosis = high hydrostatic pressure near source
  4. Low hydrostatic pressure at sink as sucrose being actively transported out of sieve tube along with water (osmosis)
    5 moves down a pressure gradient from source to sink!
33
Q

What are the ringing and tracer experiments showing?

A

Ringing plants - removal of the phloem leads to sugars accumulating above this ring in a swelling showing sugars move down the phloem not the xylem
Tracer experiments- radio active C14 used to to trace the movement of carbon containing molecules (sucrose) they show sucrose moves down the phloem.

34
Q

What are lipids and what are their main roles?

A 
There are two main groups of lipids - triglycerides and phospholipids 
Main roles: 
-source of energy
-Waterproofing 
-insulation
-protection
35
Q

What is a triglyceride? And what are the types of fatty acid?

A

Triglycerides have three fatty acid tails each forming an water bond to a glycerol molecule by condensation
Saturated- no double carbon bonds
Monounsaturated- one double carbon bond
Polyunsaturated- more than one double bond

36
Q

How are triglycerides suites to their function?

A
  • low mass:energy ratio= good storage molecule

- large and non polar so have no osmotic effect

37
Q

What are phospholipids?

What makes them different to triglycerides?

A

They have one phosphate molecule and two fatty acids attached to a glycerol molecule.
They are polar as the phosphate group is hydrophilic and the fatty acid chains are hydrophobic

38
Q

What’s the test for lipids?

A

The emulsion test:
-add 5cm3 of ethanol to the 2cm3 sample in a test tube
-shake thoroughly
-add 5cm3 of water and shake again
White cloudy suspension - presence of lipid

39
Q

What is an amino acid?

A

A molecule containing an anime group an R group and a carboxylic acid
They are the building blocks of proteins the monomers which make up the polypeptide chain

40
Q

What is the primary structure of protein?
The secondary?
The tertiary?
And the quaternary?

A

Primary- the sequence of amino acids in the polypeptide chain
Secondary - hydrogen bonding between groups in the chain forming an A helix or B pleated sheet
Tertiary - the specific 3D structure maintained by bonds such as ionic ,disulphides and hydrogen bonds
Quaternary - complex molecules containing more than one chain and possible prosthetic groups

41
Q

What’s the test for proteins?

A

The biuret test- tests for peptide bonds

  • add equal volume of biurets reagent to the sample and mix
  • purple colour indicates the presence of peptide bonds
42
Q

What factors affect enzyme rates of reaction?

A
  • temperature- increase in temp= increase in KE up to a point as enzymes denature at high temp
  • PH - (=-log10 (H+)) all enzymes have and optimum temp and a decrease or increase from this affects the rate of reaction as high or low PH alters the charge on amino acids and therefore the shape of the active site
43
Q

How does the enzyme and substrate concerntrate affect the rate of reaction on enzyme controlled reactions?

A

Enzyme conc- up to a point enzyme conc increases the rate of reaction but once all active sites are filled the rate stays the same as no more product can be made (=vmax)
Substrate conc-up to a point when substrate conc increases so does rate of reaction but once all active sites are filled and increase in substrate conc has no effect on rate

44
Q

In an enzyme controlled reaction such as the use of trypsin with milk why is the initial rate of reaction used rather than an average?

A

The rate is very rapid and the milk concentration rapidly decreases (this is the substrate conc) and comparisons can only be made at the start where control variables such as the substrate conc are the same - for all the levels of the other independent variables

45
Q

What is a serial dilution?

A

A stepwise dilution of a dilution where the dilution factor is kept constant allowing a wide range to be be covered evenly

Biology Mocks january (2 decks)

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