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30 Cards in this Set
- Front
- Back
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Q1a)i) Where in the sperm cell are the mitochondria located? 1 Marks |
-Mitochondrial sheath |
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Q1a)ii) What word describes the chromosome number in a human sperm cell? 1 Marks |
-Haploid |
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Q1b) Explain why a defective acrosome reaction may result in male infertility. 4 Marks |
-The egg is protected by the zona pellucida and follicle cells. -If acrosome reaction = defective then enzyme isn't released. -Digestive enzymes will not break down the zona pellucida. -Sperm won't be able to fuse with the oocyte membrane. |
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Q1c) Males produce large numbers of sperm cells each with a different genotype. Describe how the variation in sperm cell genotype arises. 3 Marks |
- Variation is produced in meiosis -As a result of crossing over of alleles between chromatids -The independent assortment of chromosomes |
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Q2a) The movement of materials into and out of a cell needs to be controlled. Describe what is meant by the term fluid mosaic with reference to cell membranes. 2 Marks |
-Fluid refers to the movement of phospholipids in the plane of the membrane -Mosaic refers to the random association o proteins within the membrane |
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Q2b)i) The movement of materials into and out of a cell needs to be controlled. Goblet cells lining the bronchi produce mucus. This mucus is released by exocytosis. Explain how goblet cells release mucus by exocytosis. 2 Marks |
-Mucus contained in the membrane-bound vesicles inside the cell. -These vesicles fuse to the cell membrane releasing the mucus. |
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Q2b)ii) The movement of materials into and out of a cell needs to be controlled. The consistency of the mucus is determined by the movement of water, by osmosis, from the cells lining the bronchi. Explain how the partial permeability of the surface membrane of the cells lining the bronchi allows osmosis to take place. 2 Marks |
-Partially permeable membrane is a barrier to some solutes but not water. -Enables a concentration gradient of solutes. |
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Q2b)iii) Describe how the thicker mucus would affect gas exchange across the walls of the alveoli. 2 Marks |
-Increased diffusion distance -Reduced rate of gas exchange |
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Q3a)i) What are the reactants from the LDR at PSII? H2O goes in. 1 Mark |
2H ions + 1/2O2 |
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Q3a)ii) What is the reaction called which uses H2O and provides electrons to PSII? 1 Mark |
Photolysis |
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3a)iii) Which of the following molecules are found in the PSI and PSII? ATP, ATP Synthase, Chlorophyll, RUBISCO 1 Mark |
Chlorophyll |
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Q3a)iv) In which part of the chloroplast does the reduction of NADP take place? Chloroplast outer membrane, Chloroplast stroma, Granum, Thylakoid membrane 1 Mark |
Chloroplast stroma |
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Q3a)v) Describe the role of the group membrane proteins inside the membrane. 2 Marks |
-Electron transport -Movement of hydrogen ions across thylakoid membrane -ATP production / photophosphorylation |
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Q3b)iii) Sugar cane crops are being grown for the production of biofuel. Devise an experiment to investigate the effect of light intensity on the above ground dry mass of sugar cane grown in a field. 5 Marks |
-Plant a field of sugar cane -Sample, at suitable time intervals, using randomly placed quadrats -Measure light intensity -Harvest, dry and weigh sugar cane -Record other abiotic factors |
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Q4a) Lysozyme is one component of the non-specific response to infection. Describe what is meant by a non-specific response to infection. 3 Marks |
-Response that is effective against a range of infectious diseases. -Does not involve recognition of infectious agent. -Does not react to specific antigens. |
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Q4b) Lysozyme is one component of the non-specific response to infection. A student investigated the activity of lysozyme in tears. A suspension of bacteria was mixed with molten agar and poured into a petri dish. After the agar had solidified, wells were cut and different dilutions of tear sample were placed in the wells. After 24 hours the petri dish was inspected. State the relationship between lysozyme dilution and the size of the clear zone. 1 Mark |
Positive correlation |
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Q4c) Lysozyme is one component of the non-specific response to infection. A student investigated the activity of lysozyme in tears. A suspension of bacteria was mixed with molten agar and poured into a petri dish. After the agar had solidified, wells were cut and different dilutions of tear sample were placed in the wells. After 24 hours the petri dish was inspected. Explain how the student could adapt the investigation to study the effect of pH on the activity of lysozyme. 3 Marks |
-Use buffers of different pH -Control other variables eg.temperature Compare diameter of clear zone |
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Q5a)i) Madagascar is an island rich in biodiversity. Lemurs are a diverse group of primates endemic to Madagascar. Scientists suggest there may be as many as 100 different species of lemur. State what is meant by the term endemic. 1 Mark |
Species found only in one geographical location |
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Q5a)ii) Madagascar is an island rich in biodiversity. Lemurs are a diverse group of primates endemic to Madagascar. Scientists suggest there may be as many as 100 different species of lemur. Describe what is meant by biodiversity. 2 Marks |
-A variety of species in an ecosystem -The variety of alleles in a gene pool |
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Q5a)iii) Madagascar is an island rich in biodiversity. Lemurs are a diverse group of primates endemic to Madagascar. Scientists suggest there may be as many as 100 different species of lemur. Explain how the biodiversity of lemurs in two different parts of Madagascar could be compared. 3 Marks |
-Record the number of species of lemur and the number of individuals of each species -Calculate the diversity index for each location -So the higher the index the greater the biodiversity -DNA profiling |
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Q5b) One species of lemur, the Aye-aye, is found throughout the forests of Northern Madagascar. Deforestation is taking place in this part of Madagascar. Scientists have identified 3 separate populations of Aye-aye in this area. (Map showing 3 separate populations) Explain how these 3 populations could become distinct species. 3 Marks |
-Deforestation results in geographical isolation of the populations of Aye-ayes -Resulting in reduced gene flow between the populations Different selection pressures leading to natural selection -Leading to sympatric speciation |
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Q6a) Ebola haemorrhagic fever is a life-threatening disease caused by the Ebola virus. Explain why antibiotics are not used to treat Ebola haemorrhagic fever. 2 Marks |
-Antibiotics target organelles found in bacteria -Viruses therefore are unaffected by antibiotics |
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Q6b) Ebola haemorrhagic fever is a life-threatening disease caused by the Ebola virus. Some of the blood plasma of individuals who have survived infection with Ebola can be collected. This can be used in the treatment of individuals currently infected with Ebola. Explain why blood plasma from survivors can be used to treat new cases of Ebola infection. 3 Marks |
-Survivors will have antibodies specific to the virus in their plasma -Antibodies given to individuals infected with Ebola will provide passive immunity -The antibodies provided will therefore agglutinate the virus particles |
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Q6c) Ebola haemorrhagic fever is a life-threatening disease caused by the Ebola virus. A study of the 2014 Ebola outbreak in Sierra Leone found that the Ebola virus was evolving rapidly. Explain why the evolution of the virus might reduce the effectiveness of any vaccine being developed. 4 Marks |
-Vaccine stimulates immune response to make antibodies specific to viral proteins -Mutations in the virus nucleic acid -Results in a change in the shape of the viral proteins -Therefore antibodies can no longer bind to the virus |
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Q7a) Tissues of the human body have different stem cell populations. These stem cells divide to replace and renew cells in these tissues. Describe the properties of a stem cell. 2 Marks |
-A cell that can continue to divide -Has the potential to give rise to specialised cells |
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Q7b)iv) Explain why cigarette smokers have a higher risk of developing lung cancer than non-smokers. |
-Cigarettes contain carcinogens -That increases the number of mutations in cells -Resulting in uncontrolled cell division |
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Q8a)i) Crustose coralline algae are a group of photosynthetic red algae that play an important role in the formation of coral reefs. These algae deposit calcium carbonate in their cell walls to form encrusting and rock-like structures. White an expression that describes net productivity. 1 Mark |
NPP=GPP-R |
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Q9b) Collagen is a fibrous protein. Explain how the structure of collagen is related to its function. 4 Marks |
-3 polypeptide chains tightly coiled around each other -Due to the 3rd amino acid having a small R group -Chains are held together by hydrogen bonding -Flexible without stretching due to triple helix -Chains of collagen associate together to form fibrils -Fibrils have a high tensile strength and function is to support tissues |
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Q9c)i) Fibrosis of the liver is a chronic condition that can lead to cirrhosis of the liver and liver failure. In fibrosis of the liver, liver cells secrete excess collagen. There is an association between fibrosis of the liver and alcohol consumption in humans. Scientists have investigated the effects of alcohol intake on collagen synthesis in rats. The results... Alcohol intake Synthesis of collagen None 14 Small each day 16 large one day 19 One large then small 27 Deduce the effect of alcohol intake on fibrosis of the liver in rats. 3 Marks |
-Alcohol intake increases collagen synthesis -Combined intake has greatest effect A greater level of collagen indicates greater amount of fibrosis - SO the higher the alcohol intake the greater the level of fibrosis |
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Q9c)ii) The scientists have suggest that epigenetic events are involved in resulting collagen synthesis in rats given alcohol. Explain how epigenetic events might be involved in regulating collagen synthesis in rats given alcohol. 2 Marks |
-Exposure to alcohol may result in changes of methylation of DNA / modification of histones -So that the collagen gene is more likely to be expressed |
