KCET 2017 Biology Question Paper with Answer and Solution

(A) The correct answer is $A$ (Carnivora).
In biological classification,the taxonomic hierarchy is organized as: Kingdom,Phylum,Class,Order,Family,Genus,Species.
$1$. $Carnivora$ is an order of mammals.
$2$. $Muscidae$ is a family of flies.
$3$. $Insecta$ is a class of arthropods.
$4$. $Panthera$ is a genus of big cats.

(D) The correct answer is $D$.
The Calvin cycle (also known as the $C_3$ cycle) is the light-independent reaction of photosynthesis.
For the synthesis of one molecule of glucose $(C_6H_{12}O_6)$,the cycle must turn six times.
The overall stoichiometry for the production of one glucose molecule is:
$6 CO_2 + 18 ATP + 12 NADPH + 12 H^+ \rightarrow 1 C_6H_{12}O_6 + 18 ADP + 18 Pi + 12 NADP^+ + 6 H_2O$.
Thus,the net outcome includes $1$ glucose,$18 ADP$,and $12 NADP^+$.

(B) The correct answer is $B$ $(2)$.
During the process of glycolysis,$2$ $ATP$ molecules are consumed in the preparatory phase (phosphorylation of glucose to glucose-$6$-phosphate and fructose-$6$-phosphate to fructose-$1,6$-bisphosphate).
Although $4$ $ATP$ molecules are produced in the payoff phase,the net gain is $2$ $ATP$ molecules because $2$ $ATP$ were initially utilized.

(C) The volume of air inspired or expired during a normal respiration is called Tidal Volume $(TV)$.
$TV$ is approximately $500 \ mL$ per breath.
To calculate the volume of air inspired or expired per minute,we multiply the $TV$ by the average respiratory rate (breathing rate),which is $12-16$ times per minute.
Calculation: $500 \ mL \times 12 = 6000 \ mL$ and $500 \ mL \times 16 = 8000 \ mL$.
Therefore,a healthy man can inspire or expire approximately $6000 \ mL$ to $8000 \ mL$ of air per minute.

(D) The correct answer is $D$.
Basophils are a type of granulocyte white blood cell.
They play a crucial role in inflammatory responses and allergic reactions.
They secrete chemical substances such as histamine (a vasodilator),serotonin (a neurotransmitter),and heparin (an anticoagulant) to modulate the immune response.

(D) The correct answer is $(D)$.
In a standard $ECG$,the '$P$' wave represents the electrical excitation or depolarisation of the atria,which leads to the contraction of both the atria.
The '$QRS$' complex represents the depolarisation of the ventricles,which initiates the ventricular contraction.
The '$T$' wave represents the return of the ventricles from an excited to a normal state,i.e.,the repolarisation of the ventricles. The end of the '$T$' wave marks the end of systole.

(A) The correct answer is $A$.
Parathyroid hormone $(PTH)$ and Thyrocalcitonin $(TCT)$ are the two hormones responsible for maintaining calcium homeostasis in the human body.
$PTH$ is secreted by the parathyroid glands and is a hypercalcemic hormone,meaning it increases blood $Ca^{2+}$ levels by stimulating bone resorption,renal reabsorption of $Ca^{2+}$,and intestinal absorption of $Ca^{2+}$.
$TCT$ is secreted by the thyroid gland and is a hypocalcemic hormone,which lowers blood $Ca^{2+}$ levels.
Together,these two hormones act antagonistically to maintain the precise balance of calcium in the blood.

(C) $Mycoplasma$ are the smallest known living cells.
They completely lack a cell wall,which makes them naturally resistant to antibiotics that target cell wall synthesis (like penicillin).
They are facultative anaerobes,meaning they can survive without oxygen.
Therefore,option $C$ is the correct description.

(A) The correct answer is $A$ (Rhodophyceae).
In the class $Rhodophyceae$ (red algae),asexual reproduction occurs through various types of non-motile spores.
Sexual reproduction is exclusively oogamous,involving non-motile gametes.
In contrast,$Chlorophyceae$ and $Phaeophyceae$ typically produce motile spores and gametes (flagellated) during their life cycles.

(C) flower is said to be zygomorphic when it can be divided into two similar halves only in one particular vertical plane.
Examples of zygomorphic flowers include pea,bean,Cassia,and Gulmohar.
In contrast,actinomorphic flowers (radial symmetry) are seen in Mustard,Datura,and Hibiscus.
Canna is an example of an asymmetric (irregular) flower.
Therefore,the correct option is $C$ (Gulmohar).

(B) The correct answer is $B$.
Suberin is a hydrophobic,waxy substance that provides protection and prevents water loss.
It is characteristically deposited in the cell walls of the $phellem$ (cork) cells in the stem,which are part of the periderm.
Additionally,it is deposited in the radial and tangential walls of the $endodermis$ of the root,forming the Casparian strips,which regulate the movement of water and solutes into the vascular cylinder.

(B) The correct answer is $B$ (Mitochondria).
The endomembrane system includes organelles whose functions are coordinated,such as the endoplasmic reticulum $(ER)$,Golgi complex,lysosomes,and vacuoles.
Organelles like mitochondria,chloroplasts,and peroxisomes are not considered part of the endomembrane system because their functions are not coordinated with the endomembrane components,and they do not participate in the same vesicular transport pathway.

(D) The correct answer is $D$.
Autogamy is a type of self-pollination where pollen grains are transferred from the anther to the stigma of the same flower.
For autogamy to occur,the following conditions are necessary:
$1$. The flower must be bisexual.
$2$. There must be synchrony in pollen release and stigma receptivity.
$3$. The anthers and stigma should lie close to each other.
Autogamy does not require any external pollination agents (like wind,water,or insects) because the transfer happens within the same flower.

(A) The correct answer is $A$.
Pollen grains are unicellular,haploid,and generally spherical in shape.
They typically measure about $25-50 \ \mu m$ (micrometres) in diameter.

(B) The nucellus is a diploid $(2n)$ tissue in the ovule,but in a tetraploid plant,the somatic cells are $4n$.
Given that the tetraploid plant has $4n = 48$ chromosomes in its nucellus,the haploid number $(n)$ is $48 / 4 = 12$.
The egg cell and synergids are part of the embryo sac (gametophyte) and are haploid $(n)$.
Therefore,the number of chromosomes in the egg cell is $n = 12$ and in a synergid is $n = 12$.
Wait,re-evaluating the ploidy: If the plant is tetraploid $(4n)$,the gametes produced by meiosis are diploid $(2n)$.
Thus,$4n = 48$,so $2n = 24$.
Both the egg cell and synergids are haploid relative to the sporophyte,but since the sporophyte is $4n$,the gametophyte cells are $2n$.
Therefore,both the egg cell and the synergid contain $24$ chromosomes.

$(A)$ $Statement I$ is incorrect because $RNA$ interference $(RNAi)$ is a method of cellular defence that occurs only in eukaryotic organisms, not in prokaryotes.
$Statement II$ is correct because $RNAi$ involves the silencing of specific $mRNA$ due to a complementary $dsRNA$ molecule, which prevents the translation of the $mRNA$ into protein. Thus, it is a pre-translational process.

(B) The correct answer is $B$.
$\alpha-1$ antitrypsin is a human protein used to treat emphysema.
It is produced by transgenic animals,specifically transgenic sheep.
Tracy,a transgenic sheep produced in $1997$ (often cited in literature as the first transgenic farm mammal),was engineered to express this human protein in its milk,which allows for large-scale production and purification.

$(C)$ brood parasitism.
In brood parasitism, the parasitic bird lays its eggs in the nest of its host, and the host incubates them.
During the course of evolution, the eggs of the parasitic bird have evolved to resemble the host's eggs in size and color to reduce the chances of the host bird detecting the foreign eggs and ejecting them from the nest.

(B) The correct answer is $B$.
Mac Arthur observed that $5$ closely related species of warblers living on the same tree were able to avoid competition and co-exist due to behavioral differences in their foraging activities.
This phenomenon is known as resource partitioning,where species sharing the same habitat divide resources to minimize competition and allow for coexistence.

(D) The correct answer is $D$.
Decomposition is the process by which complex organic matter is broken down into simpler inorganic substances like $CO_2$,water,and nutrients.
The rate of decomposition is significantly influenced by the chemical composition of the detritus.
If the detritus is rich in nitrogen and water-soluble substances like sugars,the decomposition process is rapid.
Conversely,if the detritus is rich in substances like lignin and chitin,the decomposition process is delayed or slower because these compounds are highly resistant to microbial degradation.

(B) The correct answer is $B$. According to the global biodiversity data provided in the $NCERT$ textbook,the number of identified fungi species is more than the combined total of the species of fishes,amphibians,reptiles,and mammals. This highlights the immense diversity of the kingdom Fungi compared to the vertebrate groups mentioned.

(A) - genetic diversity.
Genetic diversity refers to the total number of genetic characteristics within a specific species,subspecies,or group of species.
It represents the variation of genes within a species.
In the case of indigenous cows (e.g.,$Bos$ $indicus$),different breeds exist due to variations in their genetic makeup,which allows them to adapt to different environmental conditions.
Therefore,the existence of various breeds of the same species is a classic example of genetic diversity.

(B) The correct answer is $B$.
In the process of human development,the blastocyst consists of an outer layer called the trophoblast and an inner group of cells known as the inner cell mass $(ICM)$.
The trophoblast layer attaches to the endometrium and eventually forms the extraembryonic membranes and the fetal part of the placenta.
The inner cell mass differentiates into the embryo proper,which includes the three germ layers (ectoderm,mesoderm,and endoderm) that give rise to all the tissues and organs of the developing fetus.

(B) The correct answer is $B$.
Implantation is the process by which the blastocyst attaches to the endometrium of the uterus.
This process is primarily influenced and maintained by the hormone $Progesterone$,which is secreted by the corpus luteum.
$Progesterone$ prepares the endometrium for implantation and maintains pregnancy by preventing the contraction of uterine muscles.

(C) The correct answer is $C$.
During fetal development,millions of oogonia are formed in each fetal ovary.
However,no more oogonia are formed or added after birth.
Many of these primary follicles degenerate during the phase from birth to puberty.
As a result,at the time of puberty,only about $60,000-80,000$ primary follicles are left in each ovary.

(A) The female reproductive system consists of a pair of ovaries,a pair of oviducts,a uterus,a cervix,a vagina,and the external genitalia.
Among these,the accessory ducts include the oviducts (Fallopian tubes),the uterus,and the vagina.
Ovaries are the primary sex organs,not accessory ducts.
Therefore,the correct option is $A$.

(A) The correct answer is $A$.
$1$. The testes are the primary male reproductive organs responsible for the production of sperms and the secretion of male sex hormones.
$2$. The scrotum is a pouch of skin that holds the testes outside the abdominal cavity.
$3$. This external position is crucial because it maintains the temperature of the testes at $2-2.5^{\circ}C$ lower than the normal internal body temperature.
$4$. This lower temperature is essential for the process of normal spermatogenesis,as higher temperatures can inhibit sperm production.

(C) The correct answer is $1951$.
India was among the first countries in the world to initiate action plans and programs at a national level to attain total reproductive health as a social goal.
These programs,called 'family planning',were initiated in $1951$ and have been periodically assessed over the past decades.

(A) Sickle cell anaemia is caused by a point mutation in the $Hb^A$ gene.
Specifically,a single nucleotide substitution occurs in the $DNA$ sequence where the nucleotide $Adenine$ $(A)$ is replaced by $Thymine$ $(T)$.
This mutation changes the codon $GAG$ to $GTG$ at the sixth position of the $\beta$-globin chain.
Consequently,the amino acid $Glutamic$ $acid$ is replaced by $Valine$ at the sixth position of the hemoglobin protein,leading to the formation of abnormal $Hb^S$ hemoglobin.

(A) The correct answer is $A$.
Hyper-aneuploidy refers to a condition where the chromosome number is higher than the normal diploid number,specifically represented as $2n + 1$ (trisomy).
Down's syndrome is an example of autosomal hyper-aneuploidy,caused by the presence of an extra copy of chromosome $21$ (trisomy $21$).
Klinefelter's syndrome $(47, XXY)$ and Turner's syndrome $(45, X)$ are examples of sex chromosomal aneuploidy.
Haemophilia is a sex-linked recessive disorder,not an aneuploidy.

(B) In a dihybrid cross,the inheritance of two traits is considered independently. According to Mendel's Law of Independent Assortment,the alleles for seed color (Yellow $Y$ and Green $y$) segregate independently of the alleles for seed shape (Round $R$ and Wrinkled $r$).
For the seed color trait,the $F_1$ generation is heterozygous $(Yy)$. When $F_1$ plants are self-hybridized $(Yy \times Yy)$,the resulting $F_2$ generation follows a monohybrid phenotypic ratio.
The Punnett square for seed color yields: $1 YY$ (Yellow) : $2 Yy$ (Yellow) : $1 yy$ (Green).
Thus,the total number of Yellow seeds is $3$ $(1 YY + 2 Yy)$ and the total number of Green seeds is $1$ $(1 yy)$.
Therefore,the phenotypic segregation ratio of Yellow to Green seeds in the $F_2$ generation is $3:1$.

(A) The correct answer is $A$.
In honey bees,sex determination is based on the number of sets of chromosomes an individual receives.
This mechanism is known as $Haplo-diploidy$.
In this system,females (queens and workers) are diploid $(2n = 32)$ and are produced from fertilized eggs.
Males (drones) are haploid $(n = 16)$ and are produced from unfertilized eggs via parthenogenesis.

(A) The genetic code for the amino acid tryptophan is $UGG$.
During the process of translation,the anticodon on the $t-RNA$ molecule is complementary to the codon on the $mRNA$ molecule.
Since the codon is $UGG$,the complementary anticodon will be $ACC$ (where $U$ pairs with $A$,and $G$ pairs with $C$).

(B) The correct answer is $(B)$.
In the $lac$ operon,lactose or its isomer allolactose acts as an inducer.
It binds to the repressor protein,preventing it from binding to the operator region,thereby allowing the transcription of structural genes.

(B) The correct answer is $(B)$.
$DNA$ polymerase enzymes can only catalyze the addition of nucleotides in the $5^{\prime} \rightarrow 3^{\prime}$ direction.
Even during the synthesis of the lagging strand,where $DNA$ is synthesized in short fragments known as Okazaki fragments,each individual fragment is synthesized in the $5^{\prime} \rightarrow 3^{\prime}$ direction.

(C) The genome sizes of various organisms are as follows:
$1$. $\phi \times 174$ bacteriophage has $5386$ nucleotides.
$2$. Bacteriophage lambda has $48502$ base pairs (bp).
$3$. $E. coli$ has $4.6 \times 10^6$ base pairs (bp).
$4$. Human (haploid content) has $3.3 \times 10^9$ base pairs (bp).
Matching these with the given columns:
$(A) \rightarrow (s)$
$(B) \rightarrow (t)$
$(C) \rightarrow (p)$
$(D) \rightarrow (q)$
Therefore, the correct matching is $A-s, B-t, C-p, D-q$.

(A) The correct answer is $A$ (zero).
$E. coli$ replicates its $DNA$ every $20$ minutes.
Initially,the $E. coli$ cells contain $^{14}N / ^{14}N$ $DNA$.
When these cells are transferred to a medium containing $^{15}N$,the new $DNA$ strands synthesized will incorporate $^{15}N$.
After $20$ minutes (one generation),the $DNA$ molecules will be hybrid $(^{15}N / ^{14}N)$.
After $40$ minutes (two generations),the $DNA$ molecules will be a mix of hybrid $(^{15}N / ^{14}N)$ and heavy $(^{15}N / ^{15}N)$.
Since the medium only contains $^{15}N$,no new $^{14}N / ^{14}N$ $DNA$ can be formed,and the original $^{14}N$ strands will be paired with $^{15}N$ strands.
Therefore,the number of $^{14}N / ^{14}N$ $DNA$ molecules will be zero.

(A) The correct answer is $A$.
In humans,the primary transcript,known as $hnRNA$ (heterogeneous nuclear $RNA$),undergoes processing to form mature $mRNA$.
The average length of $hnRNA$ in humans is approximately $3000$ bases.

(C) The correct answer is $C$.
During the Jurassic period,the Earth's flora was dominated by gymnosperms,specifically conifers,cycads,and ferns.
These groups were highly successful and widespread,forming the primary vegetation before the later rise of angiosperms.

(D) Buried their dead.
Neanderthal man $(Homo \ neanderthalensis)$ had a brain capacity of approximately $1400 \ cc$.
They lived in the Near East and Central Asia between $1,00,000$ to $40,000$ years ago.
One of their most significant and identifiable cultural characteristics was that they buried their dead,which suggests the development of social or ritualistic behavior.

(C) Dengue and Chikungunya.
$Dengue$ is a mosquito-borne viral infection caused by the $Dengue$ virus,transmitted by infected female $Aedes$ $aegypti$ mosquitoes.
$Chikungunya$ is also a mosquito-borne viral disease. The virus is transmitted from human to human by the bite of an infected female $Aedes$ $aegypti$ mosquito.

(C) The correct answer is $C$.
Common cold is a viral infectious disease of the upper respiratory tract.
It is primarily caused by a group of viruses known as Rhinoviruses.
These viruses infect the nose and throat,leading to symptoms such as sneezing,sore throat,cough,and nasal congestion.

(C) . Latex of Poppy plant.
Morphine is a potent analgesic alkaloid obtained from the dried latex of the unripe seed capsules of the poppy plant,$Papaver$ $somniferum$.

(C) Statins.
Statins are produced by the yeast $Monascus$ $purpureus$.
They act as competitive inhibitors of the enzyme $3$-hydroxy-$3$-methylglutaryl-CoA ($HMG$-$CoA$) reductase,which is the rate-limiting enzyme in the cholesterol synthesis pathway in the liver.
By inhibiting this enzyme,statins effectively lower blood cholesterol levels.

(A) $BOD$ stands for Biochemical Oxygen Demand.
It is the amount of oxygen required by aerobic microorganisms to decompose the organic matter present in $1 \text{ litre}$ of water.
As the amount of organic matter in a water body increases,the microorganisms require more oxygen to decompose it.
Therefore,the $BOD$ increases,which serves as an indicator of water pollution.

(A) - Human gene may have introns which bacteria cannot process.
In recombinant $DNA$ technology,when a eukaryotic (human) gene is inserted into a prokaryotic host like a bacterium,the bacterium lacks the splicing machinery required to remove introns.
Since human genes contain non-coding sequences called introns,the bacterial transcription process results in a pre-mRNA that still contains these introns.
Because bacteria cannot process or splice these heterogeneous nuclear RNAs,the correct protein cannot be synthesized.

(D) The correct answer is $D$.
Restriction enzymes are named based on the genus and species of the bacterium from which they are isolated.
The first letter of the genus is written in capital letters,followed by the first two letters of the species name.
For $Sal I$,'$S$' comes from the genus $Streptomyces$ and '$al$' comes from the species $albus$.
Therefore,$Sal I$ is isolated from $Streptomyces albus$.

(A) The correct answer is $A$.
Restriction endonucleases are enzymes produced by bacteria as a defense mechanism against bacteriophages (viruses that infect bacteria).
These enzymes recognize specific $DNA$ sequences and cleave the viral $DNA$,thereby preventing the infection and replication of the virus within the bacterial cell.