TIFR GS 2023 Question Paper Biology

GS2023 - Biology Question Paper

GENERAL QUESTIONS:

In a population of a remote Pacific island, the frequency of people with green
eyes is 3%. In that same population, the frequency of people having dimples
is 0.5%. Assuming independent assortment, what is the expected number of
people who will have both dimples and green eyes, given that the population
of the island is 3400 individuals?
51
102 This question has not been taken into account for the purpose of evaluation

119
150

In a skewed distribution with a long right tail like the distribution of annual
incomes in most developing countries, which of the following statements is
true?
mean<mode<median
mean<median<mode
mode<mean<median
mode<median<mean

A bat echolocates and receives an echo 10 milliseconds later. Assuming a
speed of sound in air of 340 m/s, how far away is the object?
3.4 m
1.7 m
6.8 m
5.1 m

A badminton tournament has 128 participants and needs to produce just one
winner. In each match, only the winner goes to the next round and plays with
one of the other winners. This proceeds till ultimately there is only one winner.
How many matches will a person need to reach the semi- nals?
8
7
6
5

Kleiber’s law states that for a number of animal species, the metabolic rate,
scales as the 3/4th power of its mass. Thus, a cat that weighs about 80 times
more than a mouse:
consumes about 27 times the energy of the mouse.
consumes about 1/27 times the energy of the mouse.
consumes as much energy as the mouse.
consumes about 60 times the energy of the mouse.

Where would the graph of y=x^2 and y=x^3 intersect?
At x = -1
At all x>1
At x=0 and x=1
At all points between x=0 and x=1

Avni has 8 favorite paintings but only 2 wall hooks where she can hang them.
In how many different ways can she hang the paintings?
32
56
fi

16
64

Consider the following data as a sample.
15, 15, 33, 17, 30, 30, 20, 60, 45, 15
If each data value is increased by 5, what is the effect on the mean and
standard deviation?
Both the mean and the standard deviation increase by 5.
The mean remains the same, but the standard deviation increases by 5.
The standard deviation remains the same, but the mean increases
by 5.
Both the mean and the standard deviation remain the same

Electric cars are considered more eco-friendly because:
They do not cause air pollution
They are built from bio-degradable parts
They can carry more people
They are cheaper

A large sealed drum with a radius of 1 m and a height of 20 m, needs to be
painted all over. Assuming 1 litre of paint covers 6 square meters, how many
litres of paint will be required to paint the drum?

20 m

1m

132 litres
22 litres
20 litres
125 litres

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 pro t was 16000 and the share of Badima was INR 1600. How
many months did Badima invest in the business?
3
5
4
7

If a cat's pupils are circular, it is likely that
It is looking at a re
It is walking in darkness
It is pleading for food
It is about to sleep

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,
fi

fi

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-metre world record pace, which he completed
in 9.58 seconds.

I and II only
II and III only
I and III only
All three statements are correct.

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
white ones during the day. All flowers become pollinated. What additional
experiment can you do to support your claim?
Set up a red and white Malabar carnation at opposite ends of a
darkened flight arena to determine the flower preference of a sunbird
Set up a red and white Malabar carnation at opposite ends of a well-lit
flight arena to determine the preference of a sunbird
Cover red flowers during the day and white flowers during the
night and determine pollination
Cover only white flowers and determine the colour of the resulting
progeny.

Toxoplasma is a parasite known to induce behavioural 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 only
II only
III only
I and III only

PHYSICS

The diagram below represents a periodic wave. Which point on the wave is
90° out of phase with point P?

A
B
C
D

An electric circuit has two parallel plate capacitors (C1 and C2) in series. Both
capacitors have the same dielectric and inter-plate distance, but the plates in
C1 have a higher surface area compared to those in C2. Once fully charged,
which of the two capacitors will have a higher voltage drop?
C1
C2
The capacitor which is closer to the power supply
The capacitor which is further from the power supply

Which of the following equations best represents the graph shown below?

Y = X2
Y = ex
Y = logX
Y = X1/2

What is the value of the current I given below?

100 Ω 150 Ω
I

6V 50 Ω 200 Ω

0.01 A
0.03 A
0.02 A
0.04 A

A decibel is a measure of
The ratio of sound amplitude to sound frequency
The ratio of a pure tone to the background noise
The frequency of sound
The amplitude of sound

A bullet with the same density as water is shot straight down into a very deep
water tank. What happens after suf cient time?
The bullet eventually comes to a halt at an intermediate depth.
The bullet eventually falls to the bottom of the tank
The bullet initially moves down but eventually oats to the surface.
The bullet eventually oscillates between two depths.

Reaction P has ΔH<0 and ΔS>0 while reaction Q has ΔH>0 and ΔS>0.
Which of the following is true?
fi

fl

Both P and Q are spontaneous at all temperatures because entropy
increases.
P is spontaneous at all temperatures but Q is spontaneous only at
high temperatures.
P is spontaneous only at high temperatures but Q is spontaneous at all
temperatures.
Both P and Q are spontaneous only at high temperatures.

Evidence for the expansion of the universe comes from the observation of
light from distant galaxies. What is this observation?
Light from distant objects is red shifted
More distant pulsars have a lower orbital frequency
Light from other galaxies is focused by gravitational lensing
The number of stars per volume drops at greater distances

The wheels on a drag racing car have a higher diameter at the end of a race
than at the beginning. Which of the following is the least important factor
contributing to this?
The weight of the car is reduced due to fuel consumption.
The tires heat up so the air inside expands.
The tires rotate rapidly so the centrifugal force stretches them.
Due to rubber fatigue the stiffness of the rubber decreases.

11 balls have radii X cm, X+1 cm, …, X+10 cm. Which of the following is true
about the volumes of these balls?
The mean is equal to the median.
The mean is greater than the median.

The mean is less than the median.
The relative order of mean and median depends on the value of X.

A seagull ying 30 metres above the ocean spots a sh swimming 6 metres
below the surface. The seagull folds its wings and falls to catch the sh. What
is the velocity of the seagull when it hits the surface of the water? Assume no
air resistance.
27.5 m/s
24.25 m/s
11 m/s
588 m/s

A bacterium is swimming in an isotonic medium. I now add NaCl to a
concentration of 100 mM. Which of the following is true?
The osmotic pressure points inward but the water ows outward
The osmotic pressure points outward so the water ows outward
The osmotic pressure points inward so the water ows inward
The osmotic pressure points outward but the water ows inward

I have two identical glass beakers, X and Y, full of water. I introduce a
concentrated drop of ink into each beaker. I stir beaker Y until the ink
concentration is uniform. What can you say about the diffusive motion of the
ink molecule?
The molecule diffuses with the same diffusion coef cient in both X
and Y.
The molecule diffuses in X but not in Y.
The molecule diffuses in Y but not in X.
fl

fl

fl

fl

fi

fl

fi

fi

The molecule diffuses at the site of the original droplet but not close to
the boundary.

Elon Musk goes cycling on the moon, where there is no air resistance. He
nds a hill which has a nice smooth slope on one side, and a cliff on the
other. If he jumps off the cliff his speed is greater that when he rides to the
bottom of the slope, even though the starting height, and therefore potential
energy is the same. His cycle has no friction. What is the explanation?
The conversion of potential energy is more ef cient if the resulting
kinetic energy is along the same vector as the force due to gravity.
The distance travelled down the slope is greater, so it takes longer, so
the nal speed is slower.
The gas in his space suit applies friction even though the cycle has
none.
The wheels of the bicycle acquire kinetic energy when he rides
down the cliff.

The Pauli spin matrices are de ned as

Which of these matrices has an eigenvector [1 -1]T?

σx
σy
σz
None have real eigenvectors.
fi

fi

fi

fi

CHEMISTRY

The structure of nitrous oxide (N2O) can best be described by a resonance of
two structures. The hybridization of nitrogen atoms in the two resonance
structures are:
both sp
one sp another sp3
both sp2
one sp another sp2

Which statement is true for the following chemical reactions?
CuCO3 + heat → CuO + CO2
CuO + SnO → Cu + SnO2

CO2 is oxidised and SnO2 is reduced
CuCO3 is oxidised and CuO is reduced
CuO is oxidised and SnO is reduced
SnO is oxidised and CuO is reduced

Among the following, the one that gives a positive Iodoform test upon reaction
with I2 and NaOH is:

Correct Answer is B
Dinitrogen tetroxide (N2O4) breaks down into nitrogen dioxide (NO2). If the
reaction is reversible and endothermic, which condition will give the largest
yield of NO2?
High temperature and high pressure.
High temperature and low pressure.
Low temperature and high pressure.
Low temperature and low pressure.

The melting temperature of a human protein is 33 °C in 100 mM sodium
phosphate buffer at pH 6.5. What should the predominant conformation of the
protein in the same buffer at physiological temperature conditions be?
disordered
α helical
β sheet
Mixture of alpha helix and beta sheet.

20 μl of a 10 mg/ml solution of protein A (molecular weight 10 kDa) is added
to 20 μl of a 10 mg/ml solution of protein B of molecular weight 20 kDa. What
is the molar ratio of the two proteins (A:B) in the mixture?
1:1
2:1
1:2
2:2

When the velocity of enzyme activity is plotted against substrate
concentration, which of the following is obtained?
Hyperbolic curve
Parabola
Straight line with positive slope
Straight line with negative slope

Phosphoric acid is tribasic with three pKa values of 2.14, 6.86, and 12.4,
respectively. The ionic form of the acid that predominates at pH 3.2 is:
PO43-
HPO42-
H2PO4-
H3PO4-

If you have a polypeptide of size 11 kilo Daltons, what would be the mass of
the open reading frame that codes for the polypeptide? The average mass of
an amino acid and a nucleotide is considered to be 110 Daltons and 330
Daltons, respectively.
99990
99000
90900

99900

When the velocity of enzyme activity is plotted against substrate
concentration, which of the following is obtained?
Hyperbolic curve
Parabola
Straight line with positive slope
Straight line with negative slope

Select one of the below sets in which all the molecules show a microwave
rotational spectrum?
H2, CH4, SF6
HCl, CH3Cl, CH2Cl2, H2O
H2, HCl, CH4, CH3Cl
CH2Cl2, H2O, SF6

A tyrosine-to-histidine mutation in the active site of an enzyme signi cantly
affects its activity. The reaction is likely to be
Acid-catalysed
Base-catalysed
Free radical-catalysed
None of the above

If a branched polysaccharide (e.g. amylopectin) has 7 branch points, how
many free -OH ends are available for reduction?
7
1
6
fi

0

The Michaelis-Menten equation can be represented as follows:
v = Vmax. [S]
1 + [S]/Km
For an intracellular enzyme to function optimally, which of the following
statements regarding intracellular substrate concentration is true?

The intracellular substrate concentration should be greater than the Km
of the enzyme.
The intracellular substrate concentration should be significantly lower
than the Km of the enzyme.
The intracellular substrate concentration is independent of the Michaelis
constant Km.
The intracellular substrate concentration should be approximately
the same as that of the Km.

BIOLOGY

In a human family, the father and the mother are carriers for an autosomal
recessive disease. One of their sons is phenotypically normal. What is the
probability that this son is also a carrier?
1/2
1/3
1/4
2/3

Which of the following techniques can be used to identify a post-translational
modi cation such as phosphorylation or methylation of a protein, and the
residue where it is modi ed?
2-D gel electrophoresis
Size exclusion chromatography
Mass spectrometry
UV-Visible spectroscopy

Amino acids have different chemical properties that determine whether they
are found on the surface of globular proteins. Which of the following series of
amino acids is ordered according to how likely it will be found on the surface
of a protein:
Arginine > Leucine > Aspartic acid> Phenylalanine
Threonine > Arginine > Phenylalanine > Asparagine
Arginine > Phenylalanine > Threonine > Glycine
Aspartic acid > Threonine > Leucine > Phenylalanine

Repolarisation of membrane potential in neurons is caused by the movement
of:
fi

fi

potassium into the cell and sodium into the cell
potassium out of the cell and sodium out of the cell
potassium into the cell and sodium out of the cell
potassium out of the cell and sodium into the cell

You synthesise a short peptide [AMxVFxGNxM], where x is any amino acid
with a charged side chain. How many possible peptides can be synthesised?
15
243
125
27

Human DNA contains 18% C on a molar basis. What is the mole percentage
of A, G, and T respectively?
32, 18, 32
18, 32, 32
32, 32, 18
Insuf cient information to calculate

Which of the following statements explains why net primary productivity is
higher near the tropics?
More predators in the tropics kill herbivores, increasing plant growth in
the tropics
Increased species diversity results in increased plant growth
Availability of newly weathered inorganic nutrients
Water and warm temperatures in the tropics promote
photosynthesis
fi

The stages of the cell cycle for a cultured mammalian cell line require the
following periods of time: G1 = 8 hr, S = 5 hr, G2 = 1 hr, M = 1 hr. An
asynchronous culture of these cells is exposed to radioactive thymidine for
five minutes and then allowed to continue to grow in nonradioactive medium.
The figure below shows the results.

If the length of G2 were increased by one hour, which of the following
statements would be true regarding the slope of the line from the first
appearance of labelled mitotic cells until all cells are labelled?
It would increase.
It would decrease.
It would stay the same.
It would switch from a positive to a negative slope

X-linked recessive disorders are most commonly exhibited by ----
because-------
females, because they have two X-chromosomes and are therefore
more likely to inherit one with a disease
males, because they have only one X-chromosome
females, because one of their X-chromosomes is deactivated
both males and females, because of equal penetrance

Which of the following statement is correct, given this phylogeny of four
species?

A has gone extinct
A is more closely related to C than D
D evolved from C
B, C and D shared a common ancestor

A trihybrid test cross (order of loci unknown) produced progeny classes as
follows: 35 AbC/abc, 37 aBc/abc, 8 ABc/abc, 10 abC/abc, 3 ABC/abc, 5 abc/
abc, 1 Abc/abc, 1 aBC/abc. The gene order is
CBA
BAC
BCA
CAB

A newly discovered extra-terrestrial organism was found to contain proteins
that are made up of 75 different amino acids. Assuming that one codon codes
for a unique amino acid, which of the following is possibly correct about its
DNA and codons?

The DNA could be composed of 4 bases and the organism has a triplet
codon.
The DNA could be composed of 3 bases and the organism has a triplet
codon.
The DNA could be composed of 3 bases and the organism has a
quartet codon.
The DNA could be composed of 2 bases and the organism has a
quartet codon.

You unearth a fossilised skull. Your initial investigation suggests a reptile,
likely a dinosaur, that had strong jaw muscles. What feature led to you that
conclusion?
The presence of a sagittal crest at the top of the skull
The length of the maxilla
The shape and number of molars
Evidence of torsional strain on the tripus bone

The mutation rates due to replication error in strains A and B of Escherichia
coli are 10-8 and 10-9 per genome per generation respectively. Starting from
10 cells of each strain, the bacteria were cultured for varying amounts of time
as given below. Both strains divide once in 20 minutes. In which of these
cases would both cultures have at least one mutant bacterium?
Strain A- 520 minutes Strain B- 400 minutes
Strain A- 120 minutes Strain B- 240 minutes
Strain A- 560 minutes Strain B- 360 minutes
Strain A- 500 minutes Strain B- 560 minutes

Scientists measured the resting metabolic rate (RMR) of males and females
from 12 different insect species. Given the results shown in the figure, which
statement is correct? Circles with a cross inside indicate species that eat
plants.

In each species, males and females have similar RMR
Plant-eating insects have higher RMR than other insects
Male and female RMR is not correlated
Males generally have higher RMR than females