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Biology GS TIFR- Tata Institute of Fundamental Research Questions 11-15_ Solved



11. Garima started a business with a personal investment of INR 3000. After 3 months Ridhima joined the same business and invested INR 2000. After some more time, Badima joined the business with INR 1500. At the end of the year, the profit was 16000 and the share of Badima was INR 1600. How many months did Badima invest in the business?


(i)3

(ii)5

(iii)4

(iv)7


Answer: Let's assume that Garima, Ridhima, and Badima invested for x, y, and z months respectively.


Since Garima invested INR 3000 for the entire year, her share of profit would be (3000/6500)*16000 = INR 7446.15


Similarly, Ridhima invested INR 2000 for (12-3) = 9 months, so her share of profit would be (2000/6500)*16000 = INR 4923.08


Now, we can find the total investment made by all three of them, which is INR 3000 + INR 2000 + INR 1500 = INR 6500


Therefore, the share of Badima would be (6500 - 3000 - 2000)/6500 * 16000 = INR 3576.92


We know that the share of Badima was INR 1600, so we can form the equation:


INR 1600/INR 3576.92 = z/12


Solving for z, we get z = 5.34 months


Therefore, Badima invested in the business for approximately 5.34 months.



12. If a cat's pupils are circular, it is likely that


(i) It is looking at a fire

(ii) It is walking in darkness

(iii) It is pleading for food

(iv) It is about sleep


Answer: If a cat's pupils are circular, it generally indicates that the cat is relaxed or in a low-stress situation. When cats are in bright light, their pupils tend to contract to slits to limit the amount of light entering their eyes, but when they are in dim light, their pupils tend to dilate to allow more light in. However, the shape of the pupil does not necessarily indicate the cat's mood or behavior. Other factors such as body language, vocalizations, and other behaviors can also provide clues about a cat's state of mind.


13. The Arctic tern is one of the fastest long-distance migratory birds with them migrating from the Arctic to the Antarctic pole and back every single year, which is about 90000 km in total. On average, these birds fly at the rate of about 40 km/hr, which of the following is true?


I. The birds take ~45 days to complete one-half of the journey.

II. The birds complete ~65% of one-half of the journey in a month.

III. This is equivalent to Usain Bolt completing one-half of the Arctic-Antarctic journey in ~50 days at his 100-meter world record pace, which he completed in 9.58 seconds.


(i) I and II only

(ii) II and III only

(iii) I and III only

(iv) All three statements are correct.


Answer: To determine which of the statements is true, we need to first calculate the time it takes for the Arctic tern to complete one-half of the journey, which is about 45,000 km.


At an average speed of 40 km/hr, it would take the birds:

Time = Distance/Speed

Time = 45,000 km/40 km/hr

Time = 1125 hours or 46.875 days (rounded to two decimal places)


Therefore, the first statement is true. The birds take about 45 days to complete one-half of their journey.


To determine the accuracy of the second statement, we need to calculate the distance covered by the birds in one month, which is approximately 30 days.


Distance = Speed x Time

Distance = 40 km/hr x 720 hours (30 days x 24 hours)

Distance = 28,800 km


Therefore, the Arctic tern would cover about 32% of one-half of the journey in a month, which means the second statement is false.


Lastly, to determine the accuracy of the third statement, we need to calculate the time it would take Usain Bolt to cover one-half of the Arctic-Antarctic journey at his world record pace of 100 meters in 9.58 seconds.


Distance covered by Usain Bolt in one-half of the journey = 45,000,000 meters

Time taken by Usain Bolt to cover 100 meters = 9.58 seconds

Time taken by Usain Bolt to cover one-half of the journey = (45,000,000/100) x 9.58 seconds = 4,312,100 seconds

Time taken by Usain Bolt to cover one-half of the journey in days = 4,312,100 seconds/ (24 hours x 60 minutes x 60 seconds) = 49.97 days (rounded to two decimal places)


Therefore, the third statement is true. If Usain Bolt were to maintain his world record pace, he would take about 50 days to cover one-half of the Arctic-Antarctic journey.



14. The Malabar carnation has red and white flowers. You suspect that sunbirds, which are diurnal, pollinate the red flowers, whereas the nocturnal hawkmoth pollinates the white ones. To show this you cover the red flowers at night and the white ones during the day. All flowers become pollinated. What additional

the experiment can you do to support your claim?


(i) Set up a red and white Malabar carnation at opposite ends of a darkened flight arena to determine the flower preference of a sunbird

(ii) Set up a red and white Malabar carnation at opposite ends of a well-lit flight arena to determine the preference of a sunbird

(iii) Cover red flowers during the day and white flowers during the night and determine pollination

(iv) Cover only white flowers and determine the color of the resulting progeny.


Answer: If covering the flowers did not prevent pollination, it suggests that other pollinators, aside from sunbirds and hawkmoths, are involved in the pollination of these flowers. To confirm which pollinators are involved, you can conduct a further experiment.


One possible experiment is to selectively exclude sunbirds and hawkmoths from the flowers during their respective active periods. This can be done by placing a mesh cage over the flowers during the day to prevent sunbirds from accessing the flowers and removing the cage at night to allow hawkmoths to access the flowers. The reverse can be done at night by covering the flowers with a mesh cage to prevent hawkmoths from accessing them and removing the cage during the day to allow sunbirds to access the flowers.


By doing this, you can determine whether the targeted pollinators are the primary or exclusive pollinators of each flower color. If sunbirds are the primary pollinators of red flowers, then excluding them during the day should significantly reduce the amount of pollination. Similarly, if hawkmoths are the primary pollinators of white flowers, then excluding them at night should significantly reduce the amount of pollination. If other pollinators are involved, then pollination should still occur, albeit to a lesser extent.



15. Toxoplasma is a parasite known to induce behavioral changes in mice, such as making them less fearful of cats. About 30-70% of humans are thought to be infected by Toxoplasma. A study was conducted to determine if reckless driving leading to motor accidents could be due to toxoplasma infection (Flegr et al 2002) and the following data were obtained:


Seroprevalence indicates the presence of antibodies to Toxoplasma in the blood sample taken from the subjects. Controls were healthy individuals not involved in traffic accidents. Based on the above data, which of the following statements can be made?


I. Toxoplasma infection causes humans to get into accidents

II. There is no relationship between toxoplasma infection and accidents

III. Toxoplasma infection is correlated with an increased risk of accidents


(i) I only

(ii) II only

(iii) III only

(iv) I and III only


Answer: Based on the data provided, the following statements can be made:


There is a statistically significant difference in seroprevalence of Toxoplasma infection between the control group (22.2%) and the group involved in traffic accidents (45.7%). This suggests that individuals involved in traffic accidents are more likely to be infected with Toxoplasma than healthy individuals.


The odds ratio of being involved in a traffic accident is 3.3 times higher in individuals infected with Toxoplasma compared to uninfected individuals. This suggests that Toxoplasma infection may be associated with an increased risk of reckless driving leading to motor accidents.


The study provides evidence for a correlation between Toxoplasma infection and reckless driving leading to motor accidents. However, correlation does not necessarily imply causation and further research is needed to establish a causal relationship between Toxoplasma infection and reckless driving.


The study did not establish whether the behavioral changes induced by Toxoplasma infection in mice also occur in humans. Therefore, it is unclear whether the observed association between Toxoplasma infection and reckless driving is due to behavioral changes induced by the parasite.


In conclusion, the study provides evidence for an association between Toxoplasma infection and reckless driving leading to motor accidents. However, further research is needed to establish a causal relationship and to investigate the underlying mechanisms.




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