Biology Paper 2 Exam Style Questions with
Verified Answers
Explain why phospholipids form a bilayer. - ANSWERS- Hydrophobic fatty acid tail.
- Hydrophilic phosphate head.
- Hydrophobic tails are repelled by the charges in the polar cytoplasm and tissue fluid.
- Hydrophilic heads are attracted to the. charges in the polar cytoplasm and tissue fluid.
- Thus a bilayer is formed with hydrophobic fatty acid tails on the inside and the
hydrophilic phosphate tails on the outside.
Out of starch, glycogen and a monosaccharide, which has a high solubility in water? -
ANSWERSMonosaccharide
Describe how the cell wall in a bacterial cell differs from that in a plant cell. -
ANSWERSBacterial cell walls are made of peptidoglycan and plant cell walls are made
of cellulose.
Name the carbohydrate present in the storage granules of bacterial cells. -
ANSWERSglycogen
What organelle is:
1.A stack of curved cisternae
2. Surrounded by many vesicles
3. Used in the modification of proteins? - ANSWERSGolgi body.
What is one function of the rough endoplasmic reticulum? - ANSWERSIt is used in
protein synthesis.
State some features of the structure of chloroplasts. - ANSWERS1. Contains chlorophyll
2. Contains thylakoids
3. DNA
4. Starch granules
5. Double membrane §
Name one structure, associated with the cytoskeleton, which can bring about cell
movement. - ANSWERSFlagellum
,Explain why plasma membranes are impermeable to many biological molecules. -
ANSWERS- Some molecules must be retained within the cell.
- Other molecules that may damage the cell are prevented from entering.
- Some molecules would change the osmotic properties of the cell so must be kept
outside.
Explain why the model of membranes is called fluid. - ANSWERS- The molecules within
the membrane are able ti move freely as they are held together by hydrophobic
interactions between the phospholipids and between the phospholipids and the
proteins.
- The molecules within the membrane can move like a fluid.
Fossils provide strong evident that organisms have evolved over time. Describe other
types of evidence that support the theory of evolution. - ANSWERS- Similarities/
differences in biochemistry and genetics.
- Similarities/ differences in nucleotide/ base sequence.
- Similarities/ differences in cytochrome c.
- Similarities in sequence of amino acids in proteins.
- Similarities in any of the above implies a close relationship.
Charles Darwin sailed on HMS Beagle in its voyage around the world between 1831
and 1836.
Darwin made the following observation:
'offspring generally appear similar to their parents'.
State the conclusion that Darwin drew from this observation. -
ANSWERSCharacteristics are passed onto the next generation.
In 1859, Darwin published his book, On the Origin of Species, in which he explained
how organisms evolve by natural selection:
- Darwin's book caused controversy at the time of its publication.
- His theory of natural selection is now widely accepted by scientists.
Why is natural selection now more widely accepted by scientists than it was in the 19th
century. - ANSWERSThere is more evidence since the 19th century.
State the role of a gene. - ANSWERSCodes for a polypeptide.
Explain how the structure of DNA allows replication. - ANSWERS- Double stranded.
- Both strands act as a template.
- Hydrogen bonds can easily be broken.
- Complementary base pairing.
- Means a purine will only be able to bind to a pyrimidine.
- Due to difference sizes of purines and pyrimidines.
State the name given to the evolution of a new species. - ANSWERSSpeciation
, During the voyage of HMS Beagle, Darwin visited the Galapagos Islands off the coast of
South America.
Suggest why a higher number of species have evolved in the Galapagos Islands
compared with an area of the same size on the South American mainland. -
ANSWERSDifferent islands have different selection pressures.
In the 1970s, the technique used to clone the frogs was successfully adapted to clone
mice from embryos. Cloned mice are used to investigate factor affecting the
development and treatment. of disease.
State the advantages and disadvantages of using clones to test a treatment for a
disease. - ANSWERSAdvantages:
- Genetically identical so all react the same.
Disadvantages:
- Don't see varied response to drug lime in real populations.
- Expensive.
- Clones of mice may have an unknown health issue which would affect responses.
In the 1990s, there were further developments in cloning technology when it became
possible to make a clone of an adult mammal. The first clone produced from an adult
cell nucleus was Dolly the Sheep.
Adult cell cloning can be used to investigate the development and treatment of disease.
Outline two other potential applications of adult cell cloning. - ANSWERS1. To save/
preserve endangered species.
2. Grow/ produce tissues/ organs.
Describe, how it is possible to use selective breeding to improve the overall disease
resistance of a crop, such as potatoes, in both the short and long term. - ANSWERS-
Cross/ breed with disease resistant variety.
- Test offspring for disease resistance.
- Select offspring with resistance.
- Continue this process for many generations.
- Avoid breeding closely related individuals to preserve genetic diversity.
- Regularly cross back with wild variety.
- Preserve rate varieties in case they are needed in the future.
State the meaning of the term phylogeny and explain how phylogeny is related to
classification. - ANSWERS- Phylogeny is the study of evolutionary relationships
between organisms.
- Phylogeny is the study of the closeness of evolutionary relationships.
- Basis of modern classification.
- The closer the evolutionary relationships, the closer the taxonomic grouping.
Membranes contain a variety of proteins. Some of these proteins are combined with
carbohydrates to form glycoproteins.
Describe the functions of glycoproteins in the cell surface membrane. - ANSWERS- Act
as antigens.
Verified Answers
Explain why phospholipids form a bilayer. - ANSWERS- Hydrophobic fatty acid tail.
- Hydrophilic phosphate head.
- Hydrophobic tails are repelled by the charges in the polar cytoplasm and tissue fluid.
- Hydrophilic heads are attracted to the. charges in the polar cytoplasm and tissue fluid.
- Thus a bilayer is formed with hydrophobic fatty acid tails on the inside and the
hydrophilic phosphate tails on the outside.
Out of starch, glycogen and a monosaccharide, which has a high solubility in water? -
ANSWERSMonosaccharide
Describe how the cell wall in a bacterial cell differs from that in a plant cell. -
ANSWERSBacterial cell walls are made of peptidoglycan and plant cell walls are made
of cellulose.
Name the carbohydrate present in the storage granules of bacterial cells. -
ANSWERSglycogen
What organelle is:
1.A stack of curved cisternae
2. Surrounded by many vesicles
3. Used in the modification of proteins? - ANSWERSGolgi body.
What is one function of the rough endoplasmic reticulum? - ANSWERSIt is used in
protein synthesis.
State some features of the structure of chloroplasts. - ANSWERS1. Contains chlorophyll
2. Contains thylakoids
3. DNA
4. Starch granules
5. Double membrane §
Name one structure, associated with the cytoskeleton, which can bring about cell
movement. - ANSWERSFlagellum
,Explain why plasma membranes are impermeable to many biological molecules. -
ANSWERS- Some molecules must be retained within the cell.
- Other molecules that may damage the cell are prevented from entering.
- Some molecules would change the osmotic properties of the cell so must be kept
outside.
Explain why the model of membranes is called fluid. - ANSWERS- The molecules within
the membrane are able ti move freely as they are held together by hydrophobic
interactions between the phospholipids and between the phospholipids and the
proteins.
- The molecules within the membrane can move like a fluid.
Fossils provide strong evident that organisms have evolved over time. Describe other
types of evidence that support the theory of evolution. - ANSWERS- Similarities/
differences in biochemistry and genetics.
- Similarities/ differences in nucleotide/ base sequence.
- Similarities/ differences in cytochrome c.
- Similarities in sequence of amino acids in proteins.
- Similarities in any of the above implies a close relationship.
Charles Darwin sailed on HMS Beagle in its voyage around the world between 1831
and 1836.
Darwin made the following observation:
'offspring generally appear similar to their parents'.
State the conclusion that Darwin drew from this observation. -
ANSWERSCharacteristics are passed onto the next generation.
In 1859, Darwin published his book, On the Origin of Species, in which he explained
how organisms evolve by natural selection:
- Darwin's book caused controversy at the time of its publication.
- His theory of natural selection is now widely accepted by scientists.
Why is natural selection now more widely accepted by scientists than it was in the 19th
century. - ANSWERSThere is more evidence since the 19th century.
State the role of a gene. - ANSWERSCodes for a polypeptide.
Explain how the structure of DNA allows replication. - ANSWERS- Double stranded.
- Both strands act as a template.
- Hydrogen bonds can easily be broken.
- Complementary base pairing.
- Means a purine will only be able to bind to a pyrimidine.
- Due to difference sizes of purines and pyrimidines.
State the name given to the evolution of a new species. - ANSWERSSpeciation
, During the voyage of HMS Beagle, Darwin visited the Galapagos Islands off the coast of
South America.
Suggest why a higher number of species have evolved in the Galapagos Islands
compared with an area of the same size on the South American mainland. -
ANSWERSDifferent islands have different selection pressures.
In the 1970s, the technique used to clone the frogs was successfully adapted to clone
mice from embryos. Cloned mice are used to investigate factor affecting the
development and treatment. of disease.
State the advantages and disadvantages of using clones to test a treatment for a
disease. - ANSWERSAdvantages:
- Genetically identical so all react the same.
Disadvantages:
- Don't see varied response to drug lime in real populations.
- Expensive.
- Clones of mice may have an unknown health issue which would affect responses.
In the 1990s, there were further developments in cloning technology when it became
possible to make a clone of an adult mammal. The first clone produced from an adult
cell nucleus was Dolly the Sheep.
Adult cell cloning can be used to investigate the development and treatment of disease.
Outline two other potential applications of adult cell cloning. - ANSWERS1. To save/
preserve endangered species.
2. Grow/ produce tissues/ organs.
Describe, how it is possible to use selective breeding to improve the overall disease
resistance of a crop, such as potatoes, in both the short and long term. - ANSWERS-
Cross/ breed with disease resistant variety.
- Test offspring for disease resistance.
- Select offspring with resistance.
- Continue this process for many generations.
- Avoid breeding closely related individuals to preserve genetic diversity.
- Regularly cross back with wild variety.
- Preserve rate varieties in case they are needed in the future.
State the meaning of the term phylogeny and explain how phylogeny is related to
classification. - ANSWERS- Phylogeny is the study of evolutionary relationships
between organisms.
- Phylogeny is the study of the closeness of evolutionary relationships.
- Basis of modern classification.
- The closer the evolutionary relationships, the closer the taxonomic grouping.
Membranes contain a variety of proteins. Some of these proteins are combined with
carbohydrates to form glycoproteins.
Describe the functions of glycoproteins in the cell surface membrane. - ANSWERS- Act
as antigens.
