Questions 2011
First Tour
1. How do mammals and birds protect themselves from the bad weather?
2. In many species females live longer than males. What could be the biological meaning of this? Is the opposite situation possible? If “yes”, then in which situations? If “no”, then why?
3. Some animals and plants can detach certain organs or body parts. Why/how do they do it and why is it important for them to have this ability?
4. How can we identify the chromosome on which is located a specific gene?
5. In some cases, a change in DNA sequence can have an effect on the structure and function of a protein, but in other it does not. For each case explain why and give as many examples as you can.
6. Radio Belfast broadcasted an interview with a professor from Queen’s Centre for Cancer Research and Cell Biology. Professor Nudge, who has a reputation for a lack of prudence with his publications, said, “In our lab, we have found the origin of liver cancer! Those cells we usually call ‘cancer cells’ are in fact small, unicellular, colourless, parasitic flagellates which lost their flagella and go into amoeboid form when they enter the body. Then they colonise the human liver and become what we’ve always believed to be tumour cells! For this reason, I suggest that we increase sanitation standards for our drinking water as a preventative measure against cancer!”. What facts from Prof Nudge’s work could you check and how could you do it in order to determine the validity of his claim? In your answer consider carefully what information will be required.
Answers17/10/2011
School of Biological Sciences Bioscience Olympiad 2011
Below are some examples of answers to the first round questions. One mark was awarded for each point and each question was given a score based on 100% of the total number of possibilities. Final team scores are simply the sum of all individual question scores i.e. a team gets a total score out of 600%. This is not necessarily a complete list and answers other than those listed may have received marks.
Question 1: How do mammals and birds protect themselves from the bad weather?
1) External barrier/coverings (skin, fur, feathers, greasing, layers of fat, eyelashes etc.) + examples
2) Thermogenesis in brown fat
3) Thermogenesis by shivering
4) Sweating or evaporation from surfaces for cooling (dogs) /radiation of heat from large surfaces (elephant ears)
5) Slowing or accelerating blood circulation to cool down or heat up (limbs, ears and other extremities)
6) Shelter, either natural or self-made
7) Migration (birds fly south in winter, and whales dive deeper during storm, vultures go from the sun under clouds)
8) Sharing body heat by packing together to decrease heat emission (usually in colonial animals to protect their youngs)
9) Hibernation
10) Counter current blood circulation in whales
11) Birds perching on power lines to warm.
12) Generation of a ‘synthetic’ external barrier (elephants cover themselves in mud to prevent UV burns)
Question 2: In many species females live longer than males. What could be the biological meaning of this? Is the opposite situation possible? If “yes”, then in which situations? If “no”, then why?
1) Early death of males may be essential to decrease the competition for resources with females and vice versa.
2) Females live longer to take care of progeny. Sometimes this is the way to increase the generation change in males
3) As the result of natural selection and competition: Males are more competitive and territorial and often kill off other males.
4) Males often live more solitary lifestyles and therefore are more prone to predator attack. By itself it reduces the suppression of predators on youngs and females
5) In humans: Menstruation enables females to low iron levels and keep them from building up excess of iron in the body. Males cannot regulate excess iron in such a way and as such are more susceptible to oxidative stress.
6) Males are larger and therefore undergo more cell divisions. This leads to telomere shortening and eventual cell death.
7) Medical advances have lowered the risk of death during child birth allowing more females to live out their full lifespan.
Question 3: Some animals and plants can detach certain organs or body parts. Why/how do they do it and why is it important for them to have this ability?
Plants
1) Plants detach parts for proliferation (Fruit, spores, seeds, new baby-plants (e.g. Kalanchoe)).
2) Fallen leaves or petals (or bark) are the removal of parts that have already served their purpose. Allowing for new growth and removing the need for unnecessary metabolic energy expenditure to maintain. In desert to decrease evaporation rate. Sometimes to get rid of toxic products of metabolism.
Animals
1) Autonomy (e.g. lizards tail)
2) Removal of organs that have served their purpose (wings in ants and termites or placenta in mammals). Catastrophic metamorphosis (marine ribbon worm (Nemertea), unique ectodermal pilidium layer is detached from a larva).
3) Hectocotylus in molluscs (reproduction)
4) Epitoky in oceanic polychaetes, when new young worm is gwoeing at the end of another worm.
5) Vegetative proliferation (Flat worms)
6) Sting in bees
7) Protection (shooting of spines in porcupine)
8) Milk teeth in mammals
Question 4: How can we identify the chromosome on which is located a specific gene?
1) If the phenotype is sex-linked, then the gene is located on the sex chromosomes
2) Correlating an anomalous representation or inheritance of a certain trait with an unusual amount or morphology of a particular chromosome.
3) Active RNA synthesis from a particular chromosome can be visualised under a light microscope (using special staining) just before the expression of a certain trait.
4) If the sequence is known, it is possible to hybridise it with a cDNA (complementary DNA) chain
5) It is possible to isolate iRNA from a ribosome synthesising the protein linked to your gene of interest and use this iRNA as a probe to find a complementary DNA area in the chromosome
NB: Answers such as “Search a database of a genome of a particular animal (human) and find the location of the gene” scored 0 points.
Question 5: In some cases, a change in DNA sequence can have an effect on the structure and function of a protein, but in other it does not. For each case explain why and give as many examples as you can.
First of all, not any change would have an effect.
1) Reparation—not all changes in DNA would last long enough to be transcribed into RNA. So-called reparation system enzymes may repair DNA and correct any mistakes
2) Not all DNA encodes for protein (intrones, transport RNA, non-coding regions etc)
3) Degeneracy of the genetic code—point mutations don’t always result in amino acid changes. Multiple triplet nucleotides code for the same amino acids.
4) Even a point mutation that does affect the amino acid wouldn’t necessarily affect the protein folding. Certain amino acids with similar structures act in a similar manner (leucine and isoleucine or aspartic acid and glutamic acid). Alternatively, a change in amino acid at particular position may have no effect on structure or function at all (e.g. at the terminus of polypeptide chain).
5) Suppression of mutations by mutations in the tRNA or ribosomal RNA (less precise reading)
Question 6: Radio Belfast broadcasted an interview with a professor from Queen’s Centre for Cancer Research and Cell Biology. Professor Nudge, who has a reputation for a lack of prudence with his publications, said, “In our lab, we have found the origin of liver cancer! Those cells we usually call ‘cancer cells’ are in fact small, unicellular, colourless, parasitic flagellates which lost their flagella and do into amoeboid form when they enter the body. Then they colonise the human liver and become what we’ve always believed to be tumour cells! For this reason, I suggest that we increase sanitation standards for our drinking water as a preventative measure against cancer!”. What facts from Prof Nudge’s work could you check and how could you do it in order to determine the validity of his claim? In your answer consider carefully what information will be required.
1) To analyse the origin of cancer cells (if they are human or not), i.e. to see if cancer cells have properties of flagellate cells:
a. Can these cells return to their flagellate state i.e. grow back their flagella in certain conditions?
b. Alternative to a., if these flagellates are caught in their natural form outside of the liver, can they be grown in ‘liver-like’ conditions to induce amoeboid form? (this answer is only 0.5 points, since we do not know what flagellates they are)
c. Examine the mitosis of these ‘liver cancer’ cells. Do they divide like human cells or like Protista? In Protista, centrioles are inside the nucleus and the nuclear membrane does not disappear.
d. Check organelles such as the mitochondria. In Protista, there is often one large mitochondrion or else none at all. In humans, there is a mitochondrial network and reticulum. The same about vacuoles.
e. Check the karyotype—the number and structure of chromosomes (size, length, location of the centromeres).
f. Determine the DNA sequence (various methods are possible) to find out if the cell is human
g. Antibody studies—antibodies against flagellate proteins should bind to the ‘liver cancer’ cells or else be present in the patient’s bloodstream.
h. Protista-specific cytological stains.
2) Cancer can appear in many different tissues, however, flagellates cannot live in certain organs such as the skin, so the conclusion of Prof. Nudge is not universal.
3) «Mistake» explanation. Check for laboratory contamination by this flagellate. It is possible that they simply contaminated their samples (from dirty glassware or infected member of staff). Or check their methodology and results, it could be a methodological mistake. It’s possible that a liver cyst of parasites was mistaken for liver cancer.
4) Statistical correlation with occurrence of liver cancer from less developed countries where sanitation levels are low. Does it exist?
NB: Answers such as “the article doesn’t give any information about conditions of experiments, details of the scientific research, therefore …”, or “we have to make analysis of Prof. Nudge’s publication records” scored 0 point.