Kit Library / Science / Genetics and Breeding
⚡ Topic Learning KitShared by a Veda learner · Generated with Veda AI
Veda Bites are swipeable micro-lessons — each one teaches exactly one idea. The bites below come from this kit — swipe through them in the app.
💡 Key Idea
Traits travel from parent to child via genes.
Heredity is the transmission of characters from parents to offspring. The physical carrier of each trait is a gene — a segment of DNA on a chromosome.
↳ Each trait is controlled by a pair of alleles — one inherited from each parent.
📖 Definition
One allele can silence the other.
↳ Tt and TT both look tall, but only tt looks short.
⚙️ Process
3:1 is the magic ratio of heredity.
↳ The recessive allele is not lost in F1 — it hides and reappears in F2.
➗ Formula
3:1 — memorise this ratio.
↳ Phenotypic 3:1 and genotypic 1:2:1 always go together in a monohybrid cross.
⚙️ Process
Two traits, one 9:3:3:1 ratio.
Mendel crossed plants differing in two traits (seed shape and seed colour) to test whether traits are inherited independently.
↳ The 9:3:3:1 ratio proves traits are inherited independently of each other.
💡 Key Idea
Traits don't travel as a package.
Mendel's second law states that alleles of different genes assort independently during gamete formation — one trait's allele does not influence another's.
↳ Independent assortment is why siblings can look so different from each other.
⚖️ Comparison
One trait or two — know the difference.
↳ Dihybrid is essentially two monohybrid crosses happening together.
⭐ Important Fact
The father decides the baby's sex.
↳ Sex is determined by which sex chromosome the father's sperm carries.
⚠️ Common Mistake
Dominant doesn't mean frequent.
↳ Dominance is about expression, not frequency.
✏️ Example
Same parents, different kids.
↳ Independent assortment and random fertilisation create variation even within one family.
💡 Key Idea
No variation, no evolution.
Variation means differences in traits among individuals of a species. It arises from sexual reproduction, mutations and recombination.
↳ Evolution acts on variation — the more variation, the better a species adapts.
⚙️ Process
Survival of the best-adapted.
↳ Natural selection is differential reproduction — not 'trying' to adapt.
⚖️ Comparison
Learning to swim isn't in your genes.
↳ Only inherited traits (in DNA of germ cells) pass to the next generation.
⭐ Important Fact
Alleles separate before gametes form.
During gamete formation, the two alleles of a gene separate so each gamete carries only one allele. This is the Law of Segregation.
↳ Segregation explains why a recessive trait can reappear in the F2 generation.
🎯 Exam Tip
Ratios and diagrams win marks.
↳ Examiners reward correct ratios plus a neat Punnett square.
🧠 Memory Trick
9-3-3-1, easy as pie.
For a dihybrid F2, remember 9 : 3 : 3 : 1 — the two '3's are the new mixed combinations, and the '1' is the double recessive.
↳ 9 dominant-dominant : 3 dominant-recessive : 3 recessive-dominant : 1 recessive-recessive.
🌍 Real World
Genetics is why you look like your parents.
↳ Mendel's rules explain real inheritance patterns in humans, plants and animals.
🚫 Warning
Same look, different genes.
↳ Phenotype = what you see; genotype = the allele pair behind it.
Heredity explains how traits pass from parents to offspring through genes, alleles and chromosomes. This chapter covers Mendel's laws, dominant and recessive traits, sex determination, and how variations drive evolution.
Full explanation, worked examples & memory tricks in the app
All 17 questions, laddered from warm-up to topper-level, each with its answer and the reasoning behind it.
Q1. Which term describes the passing of traits from parents to offspring?
BeginnerA · Heredity
Heredity is the transmission of traits from parents to offspring, while variation refers to differences among individuals.
Q2. A pea plant has the genotype Tt. What is its phenotype for height?
BeginnerB · Tall
T (tall) is dominant over t (dwarf), so a Tt plant shows the dominant tall phenotype.
Q3. Which of the following is the genotypic ratio in the F2 generation of a monohybrid cross?
BeginnerD · 1:2:1
The F2 genotypic ratio is 1 TT : 2 Tt : 1 tt, i.e., 1:2:1.
Q4. What is the phenotypic ratio in the F2 generation of a monohybrid cross?
BeginnerD · 3:1
Three tall (TT or Tt) to one dwarf (tt) gives a 3:1 phenotypic ratio.
Q5. In humans, which chromosome combination results in a male child?
BeginnerB · XY
Males have one X and one Y chromosome (XY); females are XX.
Q6. Mendel's monohybrid cross on pea plants produced a 3:1 phenotypic ratio in the F2 generation.
BeginnerA · True
Mendel's monohybrid cross on pea plants produced a 3:1 phenotypic ratio in the F2 generation.
Q7. A couple has four daughters. What is the probability that their next child will be a boy?
IntermediateD · 50%
Each birth is an independent event; the probability of a boy remains 50% regardless of previous children.
Q8. Which of the following correctly describes a carrier?
IntermediateD · An individual with one dominant and one recessive allele who shows the dominant trait
A carrier is heterozygous (e.g., Tt) and shows the dominant phenotype but can pass the recessive allele to offspring.
Q9. Two parents, both with genotype Tt, have a child. What is the probability that the child will show the recessive trait?
IntermediateB · 25%
The cross Tt × Tt gives TT, Tt, Tt, tt; only tt (1 out of 4) shows the recessive trait, so probability is 25%.
Q10. In a dihybrid cross, what phenotypic ratio is observed in the F2 generation?
IntermediateB · 9:3:3:1
Mendel's dihybrid cross produced four phenotypes in a 9:3:3:1 ratio, showing independent assortment.
Q11. Which statement best explains why a recessive trait can skip a generation?
IntermediateC · Carriers show the dominant trait but can pass the recessive allele to offspring.
Heterozygous carriers (Tt) do not show the recessive trait but can transmit the recessive allele, allowing it to reappear in later generations.
Q12. A plant with genotype Tt is crossed with a plant with genotype tt. What proportion of offspring will be dwarf?
IntermediateB · 50%
The cross Tt × tt gives Tt and tt in equal numbers, so 50% are dwarf (tt).
Q13. Which of the following is a correct statement about dominant alleles?
AdvancedA · A dominant allele expresses itself even when only one copy is present.
Dominance refers to expression when one copy is present, not to frequency or disease status.
Q14. In a cross between two heterozygous tall pea plants (Tt × Tt), what is the expected ratio of tall to dwarf offspring?
AdvancedA · 3 tall : 1 dwarf
The Punnett square gives TT, Tt, Tt, tt; three show tall and one shows dwarf, so 3:1.
Q15. A woman with free earlobes (dominant trait) has a child with attached earlobes (recessive trait). What can you infer about the woman's genotype?
AdvancedC · She must be heterozygous (Ee).
To have a child with attached earlobes (ee), the mother must contribute an e allele; since she has free earlobes, she must be Ee.
Q16. Which of the following best explains why sexual reproduction is advantageous in changing environments?
AdvancedD · It generates genetic variation, which is the raw material for natural selection.
Sexual reproduction reshuffles alleles, creating variation that helps populations adapt to changing environments.
Q17. In a dihybrid cross between two pea plants, one with genotype RrYy (round yellow seeds) and another with genotype RrYy, what is the expected phenotypic ratio of the offspring?
AdvancedB · 9:3:3:1
The correct option is 9:3:3:1 because this ratio represents the expected phenotypic outcomes when two traits are independently assorted during a dihybrid cross, as demonstrated by Mendel's experiments.
26 flashcards in this kit — the app reviews them with spaced repetition so the right card returns on the right day.
Every game is built from this kit's own content — scores feed your mastery, so playing counts as studying.
Word Match
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True False
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Memory Match
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Flashcard Battle
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Speed Quiz
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Guess Term
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Sequence Builder
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Categorization
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Revision Battle
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