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Flashcards in Biology Paper 1 Deck (30):

Explain the role of the Na+/H+ pump

They both bind to separate areas

ATP hydrolysis is used to change the shape of molecule

To move Na+ against the concentration gradient allowing H+ to move in


Why does the antibiotic affect bacterial ATP synthase and not human ATP synthase

The antibiotic is made specific to the base sequence of the bacterial ATP synthase

Therefore it cannot form enzyme-substrate complexes with human ATP Synthase


Explain the shape of the curves at 50 and 60 degrees Celsius

At 60 degrees it decline more rapidly due to high amounts of heat energy causing bonds to break and causing the tertiary structure to change shape.

This means it is no longer has a complementary active site to substrate therefore ineffective

At 50 degrees the same thing happens but at a slower rate as there is less heat energy to break bonds between amino acids


Describe how glycogen is a good energy source in animals

Readily hydrolysed glycosidic bonds to give out energy and produce ATP following aerobic respiration

Has lots of ends so larger surface area for hydrolysis


Describe how ribosomes are used to make polypeptides

mRNA travels out of the nucleus and onto the rough ER where it slots into the groove between the unit and subunit of a ribosome

Ribosomes translates the mRNA

Complementary tRNA anticodon deposit amino acids that are joined by peptide bonds creating polypeptide chain


Explain all scientists results and explain why the mass increased and the p value meaning

The mass increases because the salt stayed high in the gut

Therefore the water potential decreased causing the water to move via osmosis

The p value of <0.05 means that % due to chance was less than 5% so it was significant


Increased salt results in tissue fluid build up

More molecules move out due to increased hydrostatic pressure

Water potential is lost in the tissue fluid so less tissue fluid can re enter the blood

Lymphatic system cannot completely drain the excess fluid


Describe the action of membrane bound dipeptides and explain its advantages

Hydrolyses the peptide bond between two amino acids in a dipeptide

The advantage of this is that it allows the absorption of amino acids


Describe how bacteria divides

Binary fission

Organelles, genetic material and plasmid are replicated grown and then divided and the process repeats itself


What 2 adaptations does the cell membrane in the uterine lining have that makes it efficient for nutrient transport

Has a thin membrane. Short diffusion pathways for substance

Large surface area. This increases rate of diffusion

It has lots of protein carriers


Explain how bacterial resistance arises through natural selection and why 2 antibiotics should be used

Random mutation of genes occur making bacterium resistant to one of the antibiotics

If 1 antibiotic was used then the bacterium would survive and reproduce by binary fission creating a population of resistant bacteria by passing on its resistant genes

If 2 antibiotics are used it significantly reduces the risk of antibiotic resistance and even if bacterium develops resistance to one antibiotic the other one will kill the bacterium quickly


Describe and explain the advantage of bacteria secreting extra cellular protease

Some proteins are too big to enter cells via diffusion or don’t have the specific cell membrane carrier protein

By breaking proteins down out of the cell the bacteria can take up small proteins and amino acids it needs

By secreting protease antibodies can be hydrolysed therefore protecting bacteria


Suggest how the students diagram can be improved

No shading

Draw continuous line

Cohesive labelling/ spread out labelling


Describe the role of phagocytosis in displaying antigens

Phagocyte engulf bacterium Via endocytosis

Lysosomes Fuse to vesicles

Hydrolytic enzymes are released breaking it down

Antigens makes it way to cell surface membrane to be presented


Classification of organisms



Describe how presentation of antigens leads to secretion of antibodies

Phagocytes present antibodies which trigger the helper T cells which will activate B cells

B cells divide by clonal selection producing plasma cells which secrete specific monoclonal antibodies to the antigen


How does the gill in larvae help it to be adapted to its behaviour

Counter current flow

Maximum oxygen absorption for respiration as they actively hunt for prey


State 3 methods scientists would use to determine evolutionary relationships between snakes

DNA base sequence

mRNA bade sequence

Amino acids sequence of the SAME protein


Which reaction does ATP synthase catalyse

ADP + Pi —


Which taxon do scientists disagree on



Suggest 3 environmental factors scientist would control when growing wild oat weed and wheat plants

Light intensity



Soil mineral composition


Why does viral protein lead to rheumatoid arthritis

It has a similar shape to collagen

Antibody will form a antigen-antibody complex and mark the collagen for destruction

Causes the rheumatoid arthritis to become auto immune


Why is mRNA different to pre-RNA

mRNA has been spliced therefore does not contain introns. It only contains EXONS decreasing the number of bases in it

Pre-RNA contains introns which are bases which don’t code for amino acids


What molecules are ribosomes made up of

R rna



Describe the structure of glycogen

Made up of alpha glucose

1,4 and 1,6 glycosidic bonds

Highly branched and compact making it good for storage


Compare and contrast how the TEM and optical microscope work and their limitations and strengths

Optical microscope works by shooting a beam of light at the cell where it reflects. TEM fires a beam of electrons through specimen

TEM fires beam of electrons in a vacuum so sample must be dead. Optical microscope can view living or dead tissue

TEM has a higher resolution so you can see small organelles as it has a shorter wavelength. Optical microscope has a lower resolution so you can only see large organelles such as the nucleus

TEM has a larger magnification than optical microscope


How much drug should be given to mice

Divide by 1000

Multiply by 35

Answer should be 0.75g


Describe how scientists should collect and process data to see difference in seed size

Create 2 groups. One for seeds for city trees and one for seeds for countryside trees

Measure the diameter of seeds for both groups

Find the mean diameter of each group of seeds

Find SD for both groups—


Does the data support the conclusion

Yes as there no overlap in SD

Shows that there’s no effect on membrane for wheat but more ions leave for wild oats so the membrane is disrupted

Loss of ions kills cells as no metabolic reagents


Volume of each cell following 3 days of fertilisation

(Your number)/128