Q.Intensely lactating mothers do not generally conceive due to the:

Showing the 12 most recent of 38 on this concept.

1. KCET 2026Set UNKNOWN1 markMCQ
   Q.Which of the following Sexually Transmitted Infections (STIs) are not completely curable? (A) AIDS, Genital warts (B) Chlamydiasis, Gonorrhoea (C) Genital warts, Hepatitis B (D) AIDS, Genital herpes

   ›Reveal solutionSolution

   Curability of an STI depends on its causative organism: bacterial infections respond fully to antibiotics, while the viral infections that establish persistent or lifelong infection in the body cannot be completely cured.

   Step 1 — Recall the common STIs and their causative agents

   Common STIs include gonorrhoea, syphilis, genital herpes, genital warts, chlamydiasis, trichomoniasis, hepatitis-B and HIV/AIDS. Of these, chlamydiasis and gonorrhoea are caused by bacteria.

   Step 2 — Assess curability of the bacterial infections

   Bacterial STIs like chlamydiasis and gonorrhoea are completely curable if detected early and treated properly with the correct antibiotic course, since the causative bacteria can be eliminated from the body.

   Step 3 — Assess curability of AIDS and genital herpes

   AIDS is caused by HIV and genital herpes is caused by a herpes simplex virus; both viruses integrate into or persist within host cells, so current medicine can only suppress/manage the infection (antiretroviral therapy for HIV, antivirals to reduce herpes outbreaks) — neither can be completely eliminated from the body, making them not completely curable.

   ✓Final answer

   The correct option is (D) — AIDS and Genital herpes are not completely curable.

2. KCET 2026Set UNKNOWN1 markMCQ
   Q.Which of the following statements is NOT true about 'Saheli'? (A) It is a non-steroidal preparation (B) It is a 'once-a-week' pill (C) It has low contraceptive value (D) It has fewer side effects

   ›Reveal solutionSolution

   Saheli's actual advantages are that it is non-steroidal, taken only once a week, and has few side effects with good contraceptive effectiveness — so the claim that it has low contraceptive value is the incorrect statement.

   Step 1 — Recall what Saheli is

   Saheli is an oral contraceptive developed by Indian scientists at the Central Drug Research Institute (CDRI), Lucknow. It is non-steroidal in nature, which distinguishes it from most other hormonal contraceptive pills. This matches statement (A), which is true.

   Step 2 — Check the dosage schedule

   Saheli is taken as a 'once-a-week' pill, unlike conventional oral contraceptives that require daily intake. This matches statement (B), which is true.

   Step 3 — Check its side-effect profile and efficacy

   Saheli is specifically valued because it has very few side effects and a high, not low, contraceptive value when used as prescribed. This makes statement (D) true, but directly contradicts statement (C).

   Step 4 — Identify the false statement

   Since Saheli is in fact effective (high contraceptive value) rather than weak, the statement that it 'has low contraceptive value' does not describe Saheli correctly.

   ✓Final answer

   The correct option is (C) — 'It has low contraceptive value' is NOT true about Saheli.

3. KCET 2025Set C-41 markMCQ
   Q.Choose the correct sequence of sperm transport during ejaculation (A) Seminiferous tubules $\rightarrow$ rete testis $\rightarrow$ epididymis $\rightarrow$ vasa efferentia $\rightarrow$ vas deferens $\rightarrow$ ejaculatory duct (B) Seminiferous tubules $\rightarrow$ vasa efferentia $\rightarrow$ rete testis $\rightarrow$ epididymis $\rightarrow$ vas deferens $\rightarrow$ ejaculatory duct (C) Seminiferous tubules $\rightarrow$ rete testis $\rightarrow$ epididymis $\rightarrow$ vas deferens $\rightarrow$ vasa efferentia $\rightarrow$ ejaculatory duct (D) Seminiferous tubules $\rightarrow$ rete testis $\rightarrow$ vasa efferentia $\rightarrow$ epididymis $\rightarrow$ vas deferens $\rightarrow$ ejaculatory duct

   ›Reveal solutionSolution

   Trace the male duct system in anatomical order: seminiferous tubules → rete testis → vasa efferentia → epididymis → vas deferens → ejaculatory duct.

   1. Site of production. Spermatozoa are produced in the seminiferous tubules of the testicular lobules.

   2. Rete testis. The seminiferous tubules open, through the short straight tubules (tubuli recti), into the rete testis — a network of channels inside the testis.

   3. Vasa efferentia. From the rete testis the sperm leave the testis through the vasa efferentia, which emerge from the testis and open into the epididymis.

   4. Epididymis. The vasa efferentia lead into the epididymis, located along the posterior surface of each testis, where sperm are stored and complete their maturation.

   5. Vas deferens. The epididymis is continuous with the vas deferens, which ascends into the abdomen and loops over the urinary bladder.

   6. Ejaculatory duct. The vas deferens receives the duct of the seminal vesicle to form the ejaculatory duct, which stores sperm and carries them into the urethra during ejaculation.

   So the path is:

   $\text{Seminiferous tubules}\rightarrow\text{rete testis}\rightarrow\text{vasa efferentia}\rightarrow\text{epididymis}\rightarrow\text{vas deferens}\rightarrow\text{ejaculatory duct}$

   Option (A) wrongly puts the epididymis before the vasa efferentia; (B) puts the vasa efferentia before the rete testis; (C) puts the vasa efferentia after the vas deferens. Only (D) matches the true sequence.

   ✓Final answer

   The correct option is (D) — Seminiferous tubules $\rightarrow$ rete testis $\rightarrow$ vasa efferentia $\rightarrow$ epididymis $\rightarrow$ vas deferens $\rightarrow$ ejaculatory duct.

   ANSWER: D

4. KCET 2025Set C-41 markMCQ
   Q.Out of the following options, identify which one is NOT a natural method of contraception ? (A) Implants (B) Lactational amenorrhea (C) Periodic abstinence (D) Coitus interruptus

   ›Reveal solutionSolution

   Natural methods use no device or drug; implants release progestogens from under the skin, so implants are the non-natural method.

   Step 1 — What makes a method 'natural'

   Natural / traditional methods work by avoiding the meeting of sperm and ovum — no drug, no device, no hormone. They have no side effects, but their chances of failure are high.

   Step 2 — Classify each option

   1. Periodic abstinence (C) — the couple avoids coitus from day 10 to day 17 of the cycle (the fertile period, when ovulation and hence conception is most likely). ✓ Natural.
   2. Coitus interruptus / withdrawal (D) — the male withdraws the penis before ejaculation, so semen is not deposited in the vagina. ✓ Natural.
   3. Lactational amenorrhea (B) — during intense breast-feeding after childbirth, ovulation and hence the menstrual cycle do not resume. Effective up to about six months post-partum. ✓ Natural.
   4. Implants (A) — small capsules containing progestogens (or progestogen + oestrogen) are surgically inserted under the skin; they slowly release hormone that inhibits ovulation and alters the uterine/cervical environment. ✗ This is a hormonal contraceptive, not a natural method.

   Step 3 — Conclude

   Three of the four are natural; the implant is the artificial (hormonal) one.

   ✓Final answer

   The correct option is (A) — Implants.

   ANSWER: A

5. KCET 2025Set C-41 markMCQ
   Q.In zygote intrafallopian tube transfer, the embryo upto …………. stage is transferred into the fallopian tube (A) 16 blastomeres (B) 8 blastomeres (C) 32 blastomeres (D) 2 blastomeres

   ›Reveal solutionSolution

   ZIFT transfers the zygote/early embryo up to the 8-blastomere stage into the fallopian tube; beyond 8 blastomeres the embryo goes into the uterus (IUT).

   Step 1 — Where ZIFT sits among the ART techniques

   Assisted Reproductive Technologies (ART) are used when a couple cannot conceive naturally. After in-vitro fertilisation (IVF) — the so-called 'test-tube baby' programme — the ovum is fertilised in the laboratory and the resulting embryo must be put back into the female body.

   Step 2 — The two transfer routes, split by embryo stage

   • ZIFT — Zygote Intra-Fallopian Transfer: the zygote or early embryo (up to 8 blastomeres) is transferred into the fallopian tube. The embryo is still at the stage where, naturally, it would be travelling down the fallopian tube — so the tube is the physiologically right place for it.
   • IUT — Intra-Uterine Transfer: an embryo with more than 8 blastomeres is transferred into the uterus, because by that stage the natural embryo has already reached the uterus and is preparing to implant.

   The boundary between the two is exactly 8 blastomeres — that is the fact the question is testing.

   Step 3 — Match the stem

   The stem asks for the ZIFT limit ⇒ 8 blastomeres.

   ✓Final answer

   The correct option is (B) — 8 blastomeres.

   ANSWER: B

6. KCET 2025Set C-41 markMCQ
   Q.Read the following ststements : Statement I : MTP is to get rid off wanted pregnancies due to a causal unprotected intercourse or failure of contraceptives used during coitus or rapes Statement II : MTPs are performed legally by qualified doctors by giving proper medical justification Choose the correct answer from the options given below : (A) Statements I and II are incorrect (B) Statement I is correct but Statement II is incorrect (C) Statement I is incorrect but Statement II is correct (D) Statements I and II are correct

   ›Reveal solutionSolution

   MTP (Medical Termination of Pregnancy) is meant to address UNWANTED pregnancies, not "wanted" ones — Statement I misstates this (whether from the exam's own printed wording or a scan/OCR artifact, the statement as it reads is incorrect); Statement II correctly describes the legal requirement for MTP.

   Statement I — incorrect. MTP is legally and medically intended for UNWANTED pregnancies (due to casual/unprotected intercourse, contraceptive failure, or rape) — the statement as printed says "wanted," which is not what MTP addresses.

   Statement II — correct. In India, MTPs must be performed by qualified registered medical practitioners, under specific legal conditions with proper medical justification (the MTP Act).

   ✓Final answer

   Statement I is incorrect, Statement II is correct — option (C).

7. KCET 2025Set C-41 markMCQ
   Q.Identify which one of the given pair of options is correct with respect to Down's syndrome and Turner's syndrome.

   Option	Down's syndrome symptoms	Turner's syndrome symptoms

   (a) | Short-statured individual | Gynaecomastia in man | |

   (b) | Round head, partially open mouth | Overall masculine development | |

   (c) | Broad palm, physical and mental development retarded | Sterile females with rudimentary ovaries | |

   (d) | Additional copy of an X-chromosome | Absence of an X-chromosome | (A) b (B) c (C) d (D) a

   ›Reveal solutionSolution

   Check both halves of each row: Down's = trisomy 21 (broad palm, retarded development); Turner's = 45,X0 (sterile female, rudimentary ovaries). Only row (c) gets both right, and the option naming row c is (B).

   Step 1 — Fix the two disorders firmly.

   	Down's syndrome	Turner's syndrome
   Karyotype	Trisomy of chromosome 21 — 47 chromosomes; an autosomal aneuploidy	45, X0 — one X missing; an allosomal monosomy
   Sex	Either sex	Female
   Features	Short statured, small round head, furrowed tongue, partially open mouth, broad palm with characteristic palm crease, physical, psychomotor and mental development retarded	Sterile female, rudimentary ovaries, lack of other secondary sexual characters

   A useful contrast that the wrong rows below quietly borrow from: Klinefelter's syndrome (47, XXY) is the one with an additional X chromosome and gynaecomastia (feminine breast development) in an otherwise masculine male.

   Step 2 — Test each row.

   • Row (a): Down's — "short-statured individual" ✓ (true of Down's). Turner's — "gynaecomastia in man" ✗: gynaecomastia in a male is Klinefelter's, and Turner's individuals are females. Row fails.
   • Row (b): Down's — "round head, partially open mouth" ✓. Turner's — "overall masculine development" ✗: Turner's females lack secondary sexual characters; they are not masculinised. Row fails.
   • Row (c): Down's — "broad palm, physical and mental development retarded" ✓ (classic trisomy-21 features). Turner's — "sterile females with rudimentary ovaries" ✓ (classic 45,X0 features). Both halves correct.
   • Row (d): Down's — "additional copy of an X-chromosome" ✗: Down's is an extra chromosome 21, not an extra X (an extra X is Klinefelter's). Turner's — "absence of an X-chromosome" ✓, but the row is already wrong. Row fails.

   Step 3 — Map the row to the option letter.

   Only row (c) is correct in both columns, and the option that names row c is (B).

   ✓Final answer

   The correct option is (B) — c (Down's: broad palm, physical and mental development retarded; Turner's: sterile females with rudimentary ovaries).

   ANSWER: B

8. KCET 2025Set C-41 markMCQ
   Q.The drug prescribed to the patients who have undergone organ transplant is ______ and is produced by ______. (A) Stain, Monascus purpureus (B) Cyclosporin-A, Trichoderma polysporum (C) Statin, Trichoderma polysporum (D) Cyclosporin-A, Monascus purpureus

   ›Reveal solutionSolution

   Two microbial products are commonly confused here; keep the drug and its producer paired correctly — cyclosporin-A ← Trichoderma polysporum, statin ← Monascus purpureus.

   Step 1 — Identify the drug from its clinical use.

   Organ-transplant patients need an immunosuppressant, so that the recipient's immune system does not reject the grafted organ. The bioactive molecule used as an immunosuppressive agent is cyclosporin-A. This immediately eliminates the statin options (A) and (C), because statins are used to lower blood cholesterol — they act by competitively inhibiting the enzyme responsible for cholesterol synthesis, not by suppressing immunity.

   Step 2 — Identify the producer organism.

   The two microbes to keep apart:

   Product	Produced by	Use
   Cyclosporin-A	Trichoderma polysporum (a fungus)	Immunosuppressant in organ transplant
   Statins	Monascus purpureus (a yeast)	Lowering blood cholesterol

   Step 3 — Combine.

   We need cyclosporin-A and Trichoderma polysporum in the same option:

   • (A) Statin + Monascus purpureus — a true pair, but the wrong drug for the stem (cholesterol, not transplants). ✗
   • (B) Cyclosporin-A + Trichoderma polysporum — correct drug, correct producer. ✓
   • (C) Statin + Trichoderma polysporum — both halves mismatched. ✗
   • (D) Cyclosporin-A + Monascus purpureus — right drug, wrong producer (the trap). ✗

   ✓Final answer

   The correct option is (B) — Cyclosporin-A, Trichoderma polysporum.

   ANSWER: B

9. KCET 2025Set C-41 markMCQ
   Q.With respect to limitation of Ecological pyramids, which of the following statements are correct? a) It does not take into account the same species belonging to two or more trophic levels. b) It assumes a simple food chain, something that almost never existed in nature. c) It accommodates saprophytes d) It does not accommodate a food web (A) a and b only (B) a, b and c only (C) a, b and d only (D) b, c and d only

   ›Reveal solutionSolution

   Test each statement against the four NCERT limitations of ecological pyramids; (c) is the odd one out because saprophytes are excluded from pyramids, not accommodated.

   Step 1 — Recall the limitations of ecological pyramids (NCERT, Ecosystem).

   An ecological pyramid is a neat abstraction, and its neatness is exactly its weakness:

   1. It does not take into account the same species belonging to two or more trophic levels.
   2. It assumes a simple food chain, something that almost never exists in nature.
   3. It does not accommodate a food web.
   4. Saprophytes are not given any place in ecological pyramids, even though they play a vital role in the ecosystem.

   Step 2 — Evaluate each printed statement.

   #	Statement	Verdict
   a	'Does not take into account the same species belonging to two or more trophic levels.'	TRUE — this is limitation 1 verbatim. A sparrow eating seeds and insects sits in two levels; the pyramid cannot show that. ✓
   b	'Assumes a simple food chain, something that almost never existed in nature.'	TRUE — limitation 2. ✓
   c	'It accommodates saprophytes.'	FALSE — this is the opposite of the truth. Saprophytes (decomposers) are given no place in the pyramid. The limitation is that it does not accommodate them. ✗
   d	'Does not accommodate a food web.'	TRUE — limitation 3. Real ecosystems are webs, not chains. ✓

   Step 3 — Assemble.

   The correct statements are a, b and d.

   Step 4 — Eliminate.

   • (A) a and b only — incomplete, it drops the true statement (d). ✗
   • (B) a, b and c only — includes the false (c). ✗
   • (D) b, c and d only — includes the false (c) and drops (a). ✗
   • (C) a, b and d only ✓

   The trap here is purely one of wording: (c) states a real limitation but with the negation removed.

   ✓Final answer

   The correct option is (C) — a, b and d only.

   ANSWER: C

10. KCET 2025Set C-41 markMCQ
    Q.Match the plant growth hormones of Column-I with suitable chemical derivatives present in Column-II and choose the correct option given below:

    Column-I (Hormone)	Column-II (Chemical derivative)
    a. Abscisic acid	i. Adenine derivative
    b. Gibberellins	ii. Indole acetic acid
    c. Kinetin	iii. Carotenoid derivative
    d. Auxin	iv. Terpene

    (A) a – iii, b – i, c – iv, d – ii (B) a – iii, b – iv, c – i, d – ii (C) a – iii, b – i, c – ii, d – iv (D) a – i, b – ii, c – iii, d – iv

    ›Reveal solutionSolution

    Recall the chemical parentage of the four hormones — ABA from carotenoids, gibberellins as terpenes, kinetin as a modified adenine (purine), auxin as an indole compound — and the matching follows.

    Step 1 — (a) Abscisic acid → (iii) Carotenoid derivative

    ABA is a sesquiterpenoid synthesised from a carotenoid precursor (cleavage of a xanthophyll). It is the “stress hormone”: it closes stomata under water stress, induces and maintains dormancy in seeds and buds, and antagonises gibberellins.

    Step 2 — (b) Gibberellins → (iv) Terpenes

    Gibberellins (GA₁, GA₃, … over 100 known) are diterpenoid acids — i.e. terpenes. They cause bolting, internode elongation, delay senescence, and break seed dormancy (opposing ABA).

    Step 3 — (c) Kinetin → (i) Adenine derivative

    Kinetin is a cytokinin, and cytokinins are modified purines — derivatives of adenine (kinetin itself is $N^{6}$‑furfurylaminopurine). It was discovered from autoclaved herring sperm DNA, which is exactly why it is a purine/adenine derivative. Cytokinins promote cell division and delay leaf senescence (Richmond–Lang effect).

    Step 4 — (d) Auxin → (ii) Indole acetic acid

    The natural auxin of plants is IAA — indole‑3‑acetic acid, an indole compound derived from the amino acid tryptophan. Auxins drive apical dominance, cell elongation and rooting.

    Step 5 — Assemble

    $a\to\text{iii},\quad b\to\text{iv},\quad c\to\text{i},\quad d\to\text{ii}$

    That is option (B). Option (A) swaps kinetin and gibberellin partners (b–i, c–iv), option (C) wrongly gives kinetin the indole partner, and option (D) is the trivial diagonal, which absurdly calls ABA an adenine derivative.

    ✓Final answer

    The correct option is (B) — a – iii, b – iv, c – i, d – ii.

    ANSWER: B

11. KCET 2024Set B-41 markMCQ
    Q.The process in which a small part of the vas deferens is removed or tied up through a small incision, is called (A) MTP (B) Vasectomy (C) Tubectomy (D) GIFT

    ›Reveal solutionSolution

    Vas deferens cut/tied → vasectomy (male sterilisation). The name literally contains the duct involved.

    Step 1 — Sterilisation as a contraceptive method

    Surgical sterilisation is a terminal contraceptive method — it blocks gamete transport, and is therefore highly effective but essentially irreversible. It comes in two forms:

    Procedure	Sex	Duct cut/tied	Site of incision
    Vasectomy	Male	Vas deferens	Scrotum
    Tubectomy	Female	Fallopian tube	Abdomen / vagina

    Step 2 — Match the stem

    The stem says a small part of the vas deferens is removed or tied up through a small incision. The vas deferens is the male duct that carries sperm from the epididymis to the ejaculatory duct — so cutting it prevents sperm from reaching the semen. That is vasectomy.

    Note what vasectomy does not do: it does not stop testosterone, erection, or ejaculation — only the sperm are absent from the ejaculate.

    Step 3 — Eliminate the other options

    • (A) MTP — Medical Termination of Pregnancy; an abortion, not a sterilisation, and it involves no duct.
    • (C) Tubectomy — the female counterpart, performed on the fallopian tubes, not the vas deferens. This is the main trap.
    • (D) GIFT — Gamete Intra-Fallopian Transfer, an assisted reproductive technology designed to achieve pregnancy, the exact opposite of a contraceptive.

    ✓Final answer

    The correct option is (B) Vasectomy — the male sterilisation in which the vas deferens is cut or tied.

    ANSWER: B

12. KCET 2024Set B-41 markMCQ
    Q.Find the incorrect statement among the following: (A) In sex linked recessive traits the gene is transmitted from unaffected carrier female to some of male progeny (B) Accumulation of phenylpyruvic acid in brain results in mental retardation (C) Individuals affected by Down’s Syndrome will have congenital heart defect and are more intelligent (D) Turner’s Syndrome is caused due to the absence of one X-chromosome

    ›Reveal solutionSolution

    Down's syndrome causes mental retardation — so the claim that such individuals are "more intelligent" is the incorrect statement.

    Step 1 — Evaluate (A): sex-linked recessive inheritance

    "In sex-linked recessive traits the gene is transmitted from unaffected carrier female to some of male progeny."

    For an X-linked recessive (e.g. haemophilia, colour blindness): a carrier female is $X^A X^a$ — she is unaffected because her normal allele masks the defective one. Her sons receive either $X^A$ or $X^a$, and a son who gets $X^a$ has no second X to mask it, so he is affected.

    $X^{A}X^{a} \times X^{A}Y \;\longrightarrow\; \tfrac12 \text{ sons } X^{A}Y \text{ (normal)},\; \tfrac12 \text{ sons } X^{a}Y \text{ (affected)}$

    TRUE.

    Step 2 — Evaluate (B): phenylketonuria

    "Accumulation of phenylpyruvic acid in brain results in mental retardation."

    PKU is an inborn error of metabolism: the enzyme that converts phenylalanine → tyrosine is missing. Phenylalanine therefore accumulates and is converted into phenylpyruvic acid and other derivatives, which accumulate in the brain and cause mental retardation (the excess is also excreted in urine, because renal reabsorption is poor). TRUE.

    Step 3 — Evaluate (C): Down's syndrome — the false one

    Down's syndrome arises from trisomy of chromosome 21 ($2n = 47$; an extra copy of chromosome 21, usually from non-disjunction). The affected individual is:

    • short statured, with a small round head, furrowed tongue and partially open mouth,
    • palm broad with characteristic palm crease,
    • physical, psychomotor and mental development retarded — i.e. mentally retarded,
    • often with congenital heart disease.

    So the first half of the statement (congenital heart defect) is right, but "and are more intelligent" is flatly false — the syndrome is defined in part by mental retardation. This is the incorrect statement → the answer.

    Step 4 — Evaluate (D): Turner's syndrome

    "Turner's Syndrome is caused due to the absence of one X-chromosome."

    Turner's syndrome is $45$, XO — a female missing one X ($2n = 45$, i.e. $44 + \text{XO}$). Such females are sterile, with rudimentary ovaries and lack of other secondary sexual characters. TRUE.

    Step 5 — Conclude

    Three statements are true; the one that is incorrect is (C).

    ✓Final answer

    The correct option is (C) Individuals affected by Down's Syndrome will have congenital heart defect and are more intelligent — this is the incorrect statement, as Down's syndrome involves mental retardation.

    ANSWER: C