2012 January Flashcards
Name X and Y.
2 marks
1.Granum/grana/thylakoid2. Stroma;
Describe the function of a chloroplast.(2 marks)
- Absorbs/traps/uses light;
- For photosynthesis;
- Produces carbohydrates/sugars/ lipids/protein;
Name this stage.
1 mark
Anaphase
Describe what happens during this stage that results in the production of two
genetically identical cells.(2 marks)
- Sister/identical chromatids/ identical chromosomes;
2. To (opposite) poles/ends/sides;
A sample of epithelial tissue from the small intestine of an animal was analysed.
Some of the cells had 8.4 units of DNA, others had only 4.2 units.
Use your knowledge of the cell cycle to explain why some cells had 8.4 units of DNA
and others had only 4.2 units.(2 marks)
- 8.4/cells with twice DNA content = replicated DNA / late interphase / prophase / metaphase / anaphase;
- 4.2 = DNA not replicated / (early) interphase / telophase / cell
How many different genera are shown in this diagram?(1 mark)
5;
A scientist carried out breeding experiments with catfish from different populations.
Describe how the results could show that the catfish belong to the same species.
(1 mark)
Fertile offspring produced;
The variety of colours displayed by catfish is important in courtship. Give two ways in
which courtship increases the probability of successful mating.(2 marks)
- Attracts/recognises same species;
- Attracts/recognises mate/opposite sex;
- Indication of sexual maturity/ fertility / synchronises mating;
- Stimulates release of gametes;
- Form pair bond;
What is the maximum number of amino acids for which this base sequence could code?(1 mark)
4;
Explain how this mutation leads to the formation of non-functioning PAH.(3 marks)
- Change in amino acid/(sequence of) amino acids/primary structure;
- Change in hydrogen/ionic/ disulphide bonds;
- Alters tertiary structure/active site (of enzyme);
- Substrate not complementary/cannot bind (to enzyme/active site) / no enzyme-substrate complexes form;
Use the information in the diagram to give two symptoms you might expect to be
visible in a person who produces non-functioning PAH.(2 marks)
- Lack of skin pigment / pale/light skin / albino;
2. Lack of coordination / muscles action affected;
One mutation causing phenylketonuria was originally only found in one population in
central Asia. It is now found in many different populations across Asia. Suggest how
the spread of this mutation may have occurred.(1 mark)
Founder effect / colonies split off / migration / interbreeding;
Use information in the diagram to explain why vancomycin does not affect human cells.(1 mark)
Human cells) don’t have a cell wall;
Use information in the diagram to explain how tetracycline prevents bacterial growth.(1 mark)
Affects) protein synthesis;
Frequent treatment with vancomycin can result in resistant strains of bacteria. Explain how.(3 marks)
- Mutation present/occurs;
- Resistance gene/allele;
- Resistant bacteria (survive and) reproduce;
- Vertical (gene) transmission / Horizontal (gene) transmission / conjugation;
The gene for resistance to vancomycin is very common in the bacterium Enterococcus
faecalis. The same gene has now been found in the bacterium Staphylococcus
aureus.
Use your knowledge of gene transmission to explain how the gene was passed from
one species of bacterium to another.(3 marks)
- Horizontal (gene) transmission;
- Via conjugation/pilus;
- Plasmid/Gene/DNA replicated/copied;
- Plasmid transferred (to S.aureus);
Scientists can use protein structure to investigate the evolutionary relationships
between different species. Explain why.(2 marks)
- Amino acid sequences / primary structure;
- Closer the (amino acid) sequence the closer the relationship;
- (Protein structure) related to
(DNA) base/triplet sequence;
Comparing the base sequence of genes provides more evolutionary information than
comparing the structure of proteins. Explain why.(2 marks)
- Reference to base triplets/triplet code / more bases than amino acids / longer base sequence than amino acid sequence;
- Introns / non-coding DNA;
- Degeneracy of code / more than one code for each amino acid;
Explain the importance of taking a large number of samples at each site.(1 mark)
Produces a more reliable mean/average / makes sure sample was representative / reduce effect of extreme values / identify anomalies;
Explain the importance of taking samples at random.(1 mark)
Removes bias;
Explain the effect of developing this golf course on the index of diversity of insects.(3 marks)
1. Increase in variety of plants/shrubs/grass; 2. More habitats/niches; 3. Greater variety of food sources / more food sources;
Root pressure moves water through the xylem. Describe what causes root pressure.(3 marks)
- Active transport by endodermis;
- ions/salts into xylem;
- Lowers water potential (in xylem);
- (Water enters) by osmosis;
The rate of water movement in the upper branches was different from the rate of water
movement in the trunk. Describe how.(2 marks)
- Maximum/overall rate is higher (in branches);
- Reaches maximum/peak earlier (in the day) (in branches);
- Starts higher / ends lower (in branches)
The results of this investigation support the cohesion tension theory. Explain how.(2 marks)
- Maximum/overall rate is higher (in branches);
- Reaches maximum/peak earlier (in the day) (in branches);
- Starts higher / ends lower (in branches)
Explain how oxygen is loaded, transported and unloaded in the blood.(6 marks)
- Haemoglobin carries oxygen / has a high affinity for oxygen / oxyhaemoglobin;
- In red blood cells;
- Loading/uptake/association in lungs;
- at high p.O2;
- Unloads/ dissociates / releases to respiring cells/tissues;
- at low p.O2;
- Unloading linked to higher carbon dioxide (concentration);
The larvae in this investigation were kept at a temperature of 17 oC. Why was it
important that the larvae of both species were kept at the same temperature?(2 marks)
- Allows comparison;
- (Different temperature) affects enzymes;
- (Different temperature) affects respiration/metabolism;
- (Different temperature) affects amount of dissolved oxygen;
Describe the difference in the way carbon dioxide is lost from the body of an Australian
lungfish and an African lungfish.(1 mark)
More (than in African) lost via gills in
Australian lungfish / less (than
African) lost via lungs in Australian
lungfish;
African lungfish are likely to survive for longer than Australian lungfish when living in
pools that dry up. Explain why.(2 mark)
- More/most exchange is via lungs
(in African lungfish); - Gills will not function/function less
efficiently (in air);
Apart from age, suggest two factors that the scientists should have considered when
selecting volunteers for this trial.(2 mark)
- Sex;
- Lifestyle;
- Body mass;
- Health;
- Ethnicity;
- Genetic factors / family history;
In analysing the results of this investigation, the scientists took into account the age of
the volunteers. Suggest why.(1 mark)
Age affects risk of cancer;
Tea and coffee contain caffeine. A newspaper reported the results of this investigation
under the headline ‘Caffeine helps cut cancer risk’. Explain why scientists could not
support this view solely on the basis of this investigation.(4 mark)
- Correlation does not mean causal relationship;
- Tea/coffee contains other substances;
- Contain different amounts of caffeine;
- Estimated intake (of tea/coffee);
- No control group;
- Only one type of cancer studied;
- Further studies required / only one investigation/study/group;
Another group of scientists investigated the effect of caffeine on blood flow to certain
parts of the brain. Volunteers were given different concentrations of caffeine solution
to drink. A control group was also set up. Describe how the control group should have been treated.(2 mark)
- Treated the same;
2. No caffeine;
Volunteers who drank the same concentration of caffeine solution often had different
concentrations of caffeine in their blood. Suggest one reason for the difference in
concentration of caffeine in the blood of volunteers.(1 mark)
- Absorb different amounts;
- Broken down by enzymes/digested;
- Different blood volumes;
- Differences in metabolism;
- Caffeine from a different source;
The investigation showed that caffeine reduces the blood flow to certain parts of the
brain. Suggest one way in which this could lead to a reduced risk of brain cancers(2 mark)
- Absorb different amounts;
- Broken down by enzymes/digested;
- Different blood volumes;
- Differences in metabolism;
- Caffeine from a different source;
