Class 10 Science · Chapter 8

Heredity

285 Class 10 Science questions on Heredity from the NCERT textbook, NCERT Exemplar and CBSE board papers 2017–2026, each with its answer and a step-by-step solution.

CBSE Class 10 Science previous year papers, with answers →

Questions · page 6 of 15

1. Q101 CBSE 2025
   “Sex ​of the children ​is determined ​by type ​of sex chromosome which ​they inherit from their ​father.” Justify the ​statement.
   Show answer

   The mother always gives X, so the child's sex depends on whether the father's sperm gives X or Y.

   A woman’s sex chromosomes are XX, so every egg she produces carries an X chromosome. A man’s are XY, so half his sperms carry an X and half carry a Y. If an X-bearing sperm fertilises the egg, the child is XX — a girl; if a Y-bearing sperm fertilises it, the child is XY — a boy. The mother contributes an X in every case, so the sex of the child depends on whether it inherits an X or a Y chromosome from the father, which justifies the statement.

   Step-by-step solution →
2. Q102 CBSE 2025
   Pure-tall (TT) ​pea plants are crossed with pure-dwarf (tt) pea plants. The ​pea plants obtained in $F_1$ ​generation are then self pollinated ​to produce $F_2$ ​generation.

   1. (i)What do the plants of $F_1$ generation look-like? ​Justify your answer.
   2. (ii)What is the ratio ​of pure-tall plants to pure-dwarf plants in $F_2$ generation ?
   Show answer

   (i) All ${\text{F}}_1$ plants are tall (Tt) as tallness is dominant; (ii) pure-tall : pure-dwarf plants in ${\text{F}}_2$ are 1 : 1.

   (i) All the plants of the $F_1$ generation are tall. Each receives T from the pure-tall parent and t from the pure-dwarf parent, so every $F_1$ plant is Tt, and since tallness (T) is dominant over dwarfness (t), the plant looks tall. (ii) Selfing Tt gives TT : Tt : tt = 1 : 2 : 1 in the $F_2$ generation, so the ratio of pure-tall (TT) to pure-dwarf (tt) plants is 1 : 1.

   Step-by-step solution →
3. Q103 CBSE 2025
   1. (a)​What are chromosomes ?
   2. (b)Explain in ​brief ​how ​stability of ​DNA content of ​a ​species is ensured in sexually ​reproducing organisms ?
   Show answer

   Chromosomes carry the genes; meiosis halves the number in gametes and fertilisation restores it, so the DNA content of a species stays constant.

   (a) Chromosomes are thread-like structures present in the nucleus of a cell. They are made of DNA and protein and carry the genes, the units of inheritance that pass characters from parents to offspring; each species has a fixed number of them (46, that is 23 pairs, in human beings). (b) In sexual reproduction the progeny gets genetic material from both parents, so if each parent gave its full set the DNA content would double every generation ($46\to 92\to 184\dots$). This is prevented because the germ cells (gametes) are formed by meiosis, in which the chromosome number is **halved**: each gamete carries only one chromosome of each pair ($n=23$ in human beings). When a male gamete fuses with a female gamete at fertilisation, the two haploid sets combine and the zygote regains the full diploid number ($23+23=46$). Halving in the gametes and doubling at fertilisation therefore keep the DNA content of the species constant from one generation to the next.

   Step-by-step solution →
4. Q104 CBSE 2025
   The lowest part ​of ​the ​ear called earlobe, is closely attached to the side of the head in some of us ​(Figure ‘X’), and not in others, called free earlobe (Figure ​‘Y’). Attached and free earlobes are two variants found in human populations. The gene for free earlobe is dominant over attached earlobes.

   1. (a)​A man with attached earlobes marries a woman having free ​earlobes. 50% of their children have free earlobes and ​50% have attached earlobes. Explain the inheritance of this trait and write the trait combinations of the progeny.
   2. (b)Write the gene combinations of the father and the mother in the above case.
   Show answer

   The father is $ff$ and the mother $Ff$; the progeny are $Ff$ (free earlobe) and $ff$ (attached earlobe) in the ratio $1:1$.

   (a) Free earlobe (F) is dominant and attached earlobe (f) is recessive. The father shows the recessive trait, so he is $ff$ and all his gametes carry $f$. The mother shows free earlobes, so she is $FF$ or $Ff$; if she were $FF$ every child would inherit an $F$ and all would have free earlobes, which contradicts the observation, so she must be $Ff$ and makes eggs of two kinds, $F$ and $f$. The cross $ff\times Ff$ therefore gives half $Ff$ children with free earlobes and half $ff$ children with attached earlobes, matching the observed $50\%$ and $50\%$. Trait combinations of the progeny: $Ff$ (free earlobe) and $ff$ (attached earlobe), in the ratio $1:1$. (b) Father $=ff$ (homozygous recessive); Mother $=Ff$ (heterozygous).

   Step-by-step solution →
5. Q105 CBSE 2025
   A pure pea plant having round (R), yellow ​(Y) seeds is ​crossed with another pure pea plant having wrinkled (r), green (y) seeds. Subsequently $F_1$ progeny is self-pollinated to obtain $F_2$ progeny.

   1. (a)What do the seeds of $F_1$ generation look like ​?
   2. (b)Give the possible combinations of traits in ​seeds of $F_2$ generation. Also give their ratio.
   3. (c)State ​the reason of ​obtaining ​seeds ​of new combination of traits in $F_2$ generation.
   Show answer

   ${\text{F}}_1$ seeds are all round and yellow; ${\text{F}}_2$ gives four combinations in the ratio $9:3:3:1$ because the two traits are inherited independently.

   (a) All the $F_1$ seeds are round and yellow; their genotype is $RrYy$, and round and yellow are the dominant traits. (b) The $F_2$ seeds show four combinations — round yellow, round green, wrinkled yellow and wrinkled green — in the ratio $9:3:3:1$. (c) Seed shape and seed colour are controlled by two different pairs of genes which are inherited independently of each other, so the $F_1$ plant $(RrYy)$ forms four kinds of gamete, $RY$, $Ry$, $rY$ and $ry$, in equal numbers. The recombinant gametes $Ry$ and $rY$ combine at random during fertilisation and give seeds with trait combinations that neither parent had.

   Step-by-step solution →
6. Q106 CBSE 2025
   The gene combination of purple ​flowered pea plants is ​denoted as (WW) and that of white flowered pea plants as (ww), when these two plants ​are ​crossed $F_1$ ​generation is obtained. ​

   1. (a)List two observations made by Mendel ​in $F_1$ generation plants.
   2. (b)Give the (i) percentage of white flowered plants and (ii) ratio of the gene combinations WW, Ww and ​ww in $F_2$ generation. (c) Write one difference between dominant and recessive trait.
   Show answer

   All ${\text{F}}_1$ plants were purple with no blending; 25% of ${\text{F}}_2$ plants are white, and $WW:Ww:ww=1:2:1$.

   (a) All the F1 plants bore purple flowers, so only one of the two parental traits was expressed and not one white flowered plant appeared; and no plant of an intermediate colour was seen, so the two traits had not blended. The white character was not lost but only hidden, as its reappearance in F2 shows: purple is dominant and white recessive, and the F1 plants are Ww although they look like the purple parent. (b) (i) White flowered plants in F2 $=25\%$. (ii) $WW:Ww:ww=1:2:1$. (c) A dominant trait shows itself when even one copy of its allele is present, as in Ww, whereas a recessive trait shows only when both alleles are recessive, as in ww.

   Step-by-step solution →
7. Q107 CBSE 2025
   1. (a)How many chromosomes ​are present ​in human beings ? Out of these how ​many are sex ​chromosomes ?
   2. (b)Explain how, in sexually reproducing ​organisms, the number ​of chromosomes in the progeny is ​maintained.
   Show answer

   Humans have 46 chromosomes, 2 of them sex chromosomes; halving in gametes and restoring at fertilisation keeps the number constant.

   (a) A human body cell contains $46$ chromosomes ($23$ pairs). Of these, $2$ (one pair) are sex chromosomes — XX in a female and XY in a male; the other $44$ ($22$ pairs) are alike in both sexes. (b) In sexual reproduction the progeny forms from the fusion of two gametes. If each gamete carried the full set of $46$, the zygote would have $92$ and the number would double every generation. To prevent this, the gametes (germ cells) are formed by meiosis, which halves the chromosome number: each gamete takes one chromosome of each pair, $23$ in human beings. At fertilisation a male gamete ($23$) fuses with a female gamete ($23$), and the zygote regains the full number, $23+23=46$. Halving in the gametes and restoring at fertilisation keep the number of chromosomes in the progeny the same as in the parents.

   Step-by-step solution →
8. Q108 CBSE 2025
   A ​pure ​pea plant bearing terminal ​flowers was cross-pollinated with a pure plant having axillary flowers. In ${\text{F}}_1$ generation, plants with axial ​flowers only were obtained. ${\text{F}}_1$ ​generation plants are self-pollinated and ${\text{F}}_2$ generation is obtained.

   1. (a)Work out ​the pattern of inheritance in this case.
   2. (b)What will be the ratio of plants ​obtained in ${\text{F}}_2$ generation ?
   Show answer

   Axial is dominant over terminal; ${\text{F}}_1$ is all $Aa$ and ${\text{F}}_2$ shows axial : terminal $=3:1$ (genotypes $1:2:1$).

   (a) Axial (axillary) flower position is dominant over terminal. Let $A$ stand for the factor for axial flowers and $a$ for terminal. The pure parents are axillary $AA$ and terminal $aa$; their gametes are $A$ and $a$, so every ${\text{F}}_1$ plant is $Aa$ and has axial flowers, the terminal trait staying hidden. On self-pollination each ${\text{F}}_1$ plant forms gametes $A$ and $a$ in equal numbers, and these combine to give $AA$, $Aa$, $Aa$ and $aa$ in the ${\text{F}}_2$, so the terminal trait reappears in the $aa$ plants. The two factors of a pair separate when gametes form, and the recessive trait shows only when both factors are recessive. (b) In the ${\text{F}}_2$, axial : terminal $=3:1$ by appearance (phenotypic ratio); by genes $AA:Aa:aa=1:2:1$ (genotypic ratio).

   Step-by-step solution →
9. Q109 CBSE 2025
   1. (a)“In human beings the genes inherited from the parents decide whether ​the newborn ​individual is ​male ​or female.” Explain this statement ​with the help of a flow ​diagram.
   2. (b)“Some animals rely on environmental cues for ​sex determination.” Justify this statement ​giving an example.
   Show answer

   Sex is decided by the father's sperm (X gives a girl, Y a boy); in turtles, egg temperature decides sex.

   (a) Women have a perfect pair of sex chromosomes, XX; men have a mismatched pair, XY. Every egg made by the mother carries an X, while half of the father’s sperms carry X and half carry Y. If an X-carrying sperm fertilises the egg, the child is XX, a girl; if a Y-carrying sperm fertilises it, the child is XY, a boy. So the sex chromosome the child inherits from the father decides whether it is male or female, with an equal chance of each. Flow diagram: Mother (XX) × Father (XY) → egg X; sperm X or sperm Y → X + X = XX (girl), X + Y = XY (boy). (b) In some animals the sex is decided by the environment rather than by the chromosomes inherited. In many turtles, for example, the temperature at which the fertilised eggs are kept decides whether the young are male or female: warmer eggs give mostly females and cooler eggs mostly males. In some snails, individuals can even change sex, showing that sex in them is not genetically determined.

   Step-by-step solution →
10. Q110 CBSE 2025
    In one ​of Mendalian experiments, ​when ${\text{F}}_1$ ​generation pea plants with round yellow seeds were self-pollinated, pea seeds with the ​following combinations ​were obtained ​in ${\text{F}}_2$ ​generation : Analyse the result and describe the ​mechanism of inheritance of traits which explains the above results.

    Pea seeds obtained in the F₂ generation

    Seeds	Round yellow	Round green	Wrinkled yellow	Wrinkled green
    Number	800	275	268	90

    Show answer

    Round : wrinkled and yellow : green are each about $3:1$ and the four classes about $9:3:3:1$, so the two traits are inherited independently.

    Analysis: of the $1433$ ${\text{F}}_2$ seeds, round : wrinkled $=1075:358\approx 3:1$ and yellow : green $=1068:365\approx 3:1$, so round is dominant over wrinkled and yellow over green, and each trait separates in the ${\text{F}}_2$ as a single trait does. The four classes together are $800:275:268:90\approx 9:3:3:1$, and two of them, round green and wrinkled yellow, pair the dominant form of one trait with the recessive form of the other, combinations not seen in the ${\text{F}}_1$. Mechanism: each trait is controlled by a pair of genes, one copy inherited from each parent. The ${\text{F}}_1$ plants show round yellow seeds but also carry the recessive forms ($RrYy$). When they form gametes, the two copies of each gene separate, and the genes for seed shape and seed colour are passed on independently of each other, so four kinds of gametes, $RY$, $Ry$, $rY$ and $ry$, are formed in equal numbers. Random fusion of male and female gametes gives $16$ equally likely combinations: $9$ round yellow, $3$ round green, $3$ wrinkled yellow and $1$ wrinkled green, the $9:3:3:1$ ratio of the result. Seed shape and seed colour are therefore inherited independently of each other.

    Step-by-step solution →
11. Q111 CBSE 2025
    Mendel ​used a number of visible contrasting characters of pea plants (Tall/Short plants, Round/Wrinkled seed, ​Violet/White flowers, etc.) for his experiments and worked out the rules ​of ​heredity. He conducted several experiments by making a ​cross with one or two pairs of visible contrasting characters of pea plants. On the basis of his observations, Mendel gave some interpretations which are helpful in the ​study ​of mechanism of inheritance of traits of different organisms.

    1. (a)When Mendel crossed pure tall pea plants (TT) with pure short pea plants (tt) to obtain $F_1$ progeny plants, which two characteristics did he observe in $F_1$ progeny plants?[1]
    2. (b)Differentiate between dominant and recessive traits.[1]
    3. (c)(i)Consider the following cross with two pairs of contrasting characters: RRYY (Round yellow) $\times$ rryy (Wrinkled green). In this cross, Mendel observed four different combinations of pea seeds in $F_2$ generation pea plants. State the method used by Mendel to obtain $F_2$ progeny. Write the new traits found in $F_2$ progeny. State the conclusion that was drawn from this experiment.[2]
    4. (c)(ii)OR : “It is possible that a trait is inherited, but may not be expressed.” Justify this statement.[2]
    Show answer

    All $F_1$ plants are tall; selfing $\text{RrYy}$ gives $9:3:3:1$ in $F_2$, so seed shape and colour are inherited independently.

    (a) All the $F_1$ plants were tall, so only one parental trait (tallness) appeared; and no plant was short or of intermediate height - the traits did not blend, although every $F_1$ plant carried both alleles (Tt). (b) A dominant trait expresses itself even when only one copy of its allele is present, so it shows in the hybrid Tt - for example tallness; a recessive trait is masked in the hybrid and appears only when both alleles are recessive, tt - for example shortness. (c)(i) Mendel obtained the $F_2$ by self-pollinating the $F_1$ plants (RrYy, round yellow). The new traits in the $F_2$ are round green seeds and wrinkled yellow seeds, which appear alongside the parental round yellow and wrinkled green in the ratio 9 : 3 : 3 : 1. The conclusion drawn is that seed shape and seed colour are inherited independently of each other. OR (c)(ii) A trait is controlled by a pair of alleles, one from each parent. A recessive allele is masked whenever a dominant allele is present with it, so it is inherited without being expressed. Every $F_1$ plant of TT $\times$ tt receives t from the short parent yet is tall; the hidden allele is not lost, and on selfing the $F_1$ one quarter of the $F_2$ plants are tt and short again.

    Step-by-step solution →
12. Q112 CBSE 2025
    The process of determining the sex ​of a ​newborn is purely genetic. But still many people in some societies believe that only the woman (mother) ​is responsible for determination ​of the sex of the ​child and blame her. In ​fact, the ​sex of ​the child is genetically determined. But there are some animals where sex is not genetically determined.

    1. (a)Define sex chromosomes.[1]
    2. (b)Mention one example of animals where sex is not genetically determined. How is sex determined in these animals ? Explain.[1]
    3. (c)(i)Does the genetic combination of the mother play a significant role in determining the sex of newborn ? Explain.[2]
    4. (c)(ii)OR : How is equal genetic contribution of male and female parents ensured in progeny ?[2]
    Show answer

    Sex chromosomes (XX, XY) decide sex; turtle sex depends on egg temperature; the father's sperm decides a child's sex; each parent gives 23 chromosomes.

    (a) Sex chromosomes are the pair of chromosomes that determines the sex of an individual, as opposed to the autosomes, which are alike in both sexes. In human beings they are the twenty-third of the 23 pairs: a female has two X chromosomes (XX) and a male has one X and one Y chromosome (XY). (b) Turtles are one such example (crocodiles and some lizards behave in the same way); snails are another. In turtles the sex is not fixed by the chromosomes but by the environment: the temperature at which the fertilised eggs are incubated during the embryo's development decides whether the young that hatch are males or females. In a snail, an individual can itself change sex. (c)(i) No. The mother is XX, so every egg she produces necessarily carries an X chromosome and she has no other kind of egg to give. The father is XY, so half his sperms carry X and half carry Y. An X-bearing sperm gives an XX zygote, a girl, and a Y-bearing sperm gives an XY zygote, a boy, in equal proportion. The sex of the newborn is therefore decided by the father's sperm, and the mother's genetic combination plays no part in it. (c)(ii) Each parent contributes exactly one chromosome of every pair. A human body cell has 23 pairs, that is 46 chromosomes; during the formation of the germ cells this number is halved, so the egg carries 23 chromosomes and the sperm carries 23; at fertilisation they fuse and the zygote regains 23 + 23 = 46. Since one chromosome of every pair comes from the mother and the other from the father, the progeny inherits one copy of each gene from each parent, which is what makes the genetic contribution of the two parents equal.

    Step-by-step solution →
13. Q113 CBSE 2025
    In human beings, there are 23 pairs of chromosomes. Out of these 23 pairs of chromosomes (i.e. ​46 ​chromosomes), 22 pairs of chromosomes are called autosomes and one pair of chromosomes. ​i.e. two chromosomes are called sex chromosomes. The sex chromosomes are of two types — ‘X’ chromosomes ​and ‘Y’ ​chromosomes. The sex of a child ​(i.e. progeny), is decided at ​the time of fertilisation. In other words, at the time of zygote formation the sex chromosomes inherited from the parents of a child decide ​whether the new born will be a boy or a girl.

    1. (a)What are chromosomes ?[1]
    2. (b)Why is the pair of sex chromosomes in human males called mismatched pair ?[1]
    3. (c)(i)Show with the help of a flow chart that the statistical probability of getting a boy or a girl is 50 : 50.[2]
    4. (c)(ii)OR : Mention two examples of animals where sex is not determined genetically like human beings. Describe in brief the method of sex determination in these animals.[2]
    Show answer

    Chromosomes carry genes; the male XY pair is mismatched; boys and girls are $50:50$; turtles and snails show non-genetic sex.

    (a) Chromosomes are thread-like structures present in the nucleus of a cell, made of DNA and protein, which carry the genes and are passed on from the parents to the offspring; a human cell carries $23$ pairs of them. (b) In a human male the sex-chromosome pair is one X and one Y. The Y is much smaller than the X and carries a different set of genes, so the two members of the pair are unlike each other, unlike the matched XX pair of a female - which is why it is called a mismatched pair. (c)(i) The mother is $44+\text{XX}$, so every egg is $22+\text{X}$; the father is $44+\text{XY}$, so half his sperms are $22+\text{X}$ and half are $22+\text{Y}$. An egg fertilised by an X-bearing sperm gives $44+\text{XX}$, a girl, and by a Y-bearing sperm gives $44+\text{XY}$, a boy. The two kinds of sperm are equally frequent, so $P(\text{girl})=P(\text{boy})=\frac{1}{2}$, that is $50:50$. (c)(ii) Turtles and snails. In turtles the sex of the young is decided by the temperature at which the fertilised eggs are incubated - warmer nests give females and cooler nests give males - and not by the chromosomes inherited. In snails an individual can change its sex during its life, functioning as a male at one time and as a female at another, so sex is not fixed genetically at all.

    Step-by-step solution →
14. Q114 CBSE 2025
    More than a century ago Gregor ​Johann Mendel worked out the main rules of ​heredity by working on the garden pea plants using a number of visible ​contrasting characters-round / wrinkled seeds, short/tall plants, violet/white ​flowers and ​so on. He conducted a number of experiments by ​making a cross with one or two pairs of ​contrasting characters of the pea plants. On the basis of his observations, Mendel made certain conclusions which helped him to arrive at the ​laws of inheritance.

    1. (a)In a cross between violet flowered pea plants (VV) and white flowered pea plants (ww), state the characteristics of the plants obtained in $F_1$ progeny.
    2. (b)If the plants of $F_1$ progeny obtained in (a) are self-pollinated, in what ratio would the plants with gene combinations (VV) and (Vw) observed in the plants of $F_2$ progeny ?
    3. (c)(i)If 800 plants are produced in $F_2$ progeny of the above mentioned cross, how many plants will show the recessive character ? Justify your answer.
    4. (c)(ii)OR : Justify the statement “Sex of the children in human beings will be determined by the chromosome they inherit from their father”.
    Show answer

    $F_1$ plants are all violet ($Vw$); $VV:Vw=1:2$; 200 of 800 $F_2$ plants are white; the father's sex chromosome decides the child's sex.

    (a) All the $F_1$ plants have the gene combination $Vw$, all are heterozygous, and all bear violet flowers, resembling only the violet parent; the white character is carried but hidden because violet is dominant. (b) $VV:Vw=1:2$ (the full $F_2$ genotypic ratio being $VV:Vw:ww=1:2:1$). (c)(i) $200$ plants. The $F_2$ genotypes are $1VV:2Vw:1ww$, and the recessive white character shows only in the $ww$ plants, which are one in four, so $800\times \frac{1}{4}=200$. (c)(ii) A mother is $XX$, so every egg carries an X; a father is $XY$, so half his sperms carry X and half carry Y. An X-bearing sperm gives $XX$, a girl, and a Y-bearing sperm gives $XY$, a boy. The mother can contribute only X in every case, so the sex of the child is decided entirely by the sex chromosome inherited from the father, with a $50:50$ chance either way.

    Step-by-step solution →
15. Q115 CBSE 2024
    Consider ​the following statements :

    1. (i)The sex of a child is ​determined by ​what it inherits from the mother.
    2. (ii)The sex of a child ​is determined by what ​it inherits from the father.
    3. (iii)The probability of having a male child is more than that ​of a female child.
    4. (iv)The sex of a child is determined at the time of fertilisation when male and female gametes fuse to form a ​zygote. The correct statements are :

    1. (a)(i) and (iii)
    2. (b)(ii) and (iv)
    3. (c)(iii) and (iv)
    4. (d)(i), (iii) and (iv)
    Show answer

    (b) (ii) and (iv)

    Step-by-step solution →
16. Q116 CBSE 2024
    Chromosomes :

    1. (i)carry hereditary ​information ​from parents ​to the ​next generation.
    2. (ii)​are thread like structures located ​inside the nucleus of an animal cell.
    3. (iii)​always exist ​in pairs in human reproductive cells.
    4. (iv)are involved in the process of cell division. The correct statements are :

    1. (a)(i) and (ii)
    2. (b)(iii) and (iv)
    3. (c)(i), (ii) and (iv)
    4. (d)(i) and (iv)
    Show answer

    (c) (i), (ii) and (iv)

    Step-by-step solution →
17. Q117 CBSE 2024
    In an experiment to study ​independent inheritance of ​two separate traits ​: shape ​and colour of seeds, ​the ​ratio of the different combinations in ${\text{F}}_2$ ​progeny would be

    1. (a)1 : 3
    2. (b)1 : 2 : 1
    3. (c)9 : 3 : 3 : 1
    4. (d)9 : 1 : 1 : 3
    Show answer

    (c) 9 : 3 : 3 : 1

    Step-by-step solution →
18. Q118 CBSE 2024
    Select the correct statements regarding the ​cross between ​a ​pure tall pea ​plant and a pure short pea plant ​in Mendelian experiments : I. ​For the same trait, two copies of genes are present in individuals that reproduce sexually. II. The tall plants of ${\text{F}}_1$ generation were exactly the same as the tall ​plants of the parent generation genetically. III. One-quarter of the plants of ${\text{F}}_2$ generation were short. IV. Traits like tallness and shortness both were inherited in the plants of ${\text{F}}_1$ generation.

    1. (a)I and II
    2. (b)II and III
    3. (c)I, II and III
    4. (d)I, III and IV
    Show answer

    (d) I, III and IV

    Step-by-step solution →
19. Q119 CBSE 2024
    A cross made ​between two pea ​plants ​produces 50% tall and 50% short pea plants. The gene combination ​of the parental pea plants ​must be

    1. (a)Tt and Tt
    2. (b)TT and Tt
    3. (c)Tt and tt
    4. (d)TT and tt
    Show answer

    (c) Tt and tt

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20. Q120 CBSE 2024
    A ​cross between two ​tall pea plants resulted ​in ​offsprings having a few dwarf ​plants. The ​gene-combination of the parental plants ​must be

    1. (a)Tt and Tt
    2. (b)Tt and tt
    3. (c)TT and tt
    4. (d)TT and Tt
    Show answer

    (a) Tt and Tt

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