Basic Principles of Inheritance
Class 11 · Biotechnology
4 ideas in Class 11 Biotechnology, explained in plain words, with games and quizzes to practise.
Mendel's Laws
Part of: Pea Rules
Mendel selfed seven pea traits into pure lines over nine years, publishing 1866 and rediscovered 1900. Tall by dwarf gives all tall F1 then 3 to 1 with genotypes 1 to 2 to 1, proving dominance and segregation; recessive crosses reveal hidden genotypes.
Why it matters. Ratio reading plus test-cross logic starts genetics.
Formulas
- F2 phenotype ratio is 3 dominant to 1 recessive
- F2 genotype ratio is 1 to 2 to 1
- Test cross of mixed tall gives 1 to 1
Key words
- Allele
- : One of two gene forms.
- Homozygous
- : Two identical alleles.
- Heterozygous
- : Two different alleles.
- Genotype
- : Allele pair held.
- Phenotype
- : Visible trait shown.
- Test cross
- : Cross with recessive parent.
Try it in two minutes
- Self pure lines.
- Count 3 to 1.
- Test unknown talls.
Try at home. Explain why TT and Tt look alike.
More Patterns
Part of: Pea Rules
Mirabilis red by white yields pink F1 and 1 to 2 to 1, while roan coats and MN groups co-express both alleles. Two traits assort into 9 to 3 to 3 to 1 with new combos proving independence, and round-yellow homozygous by heterozygous gives all dominant.
Why it matters. Ratio shifts signal which pattern questions test.
Key words
- Incomplete dominance
- : Intermediate heterozygote trait.
- Codominance
- : Both alleles expressed together.
- Roan
- : Mixed red-white coat.
- Dihybrid
- : Two-trait cross.
- Independent assortment
- : Traits inherited separately.
Try it in two minutes
- Pink the middles.
- Show both sides.
- Multiply 3 by 3.
Try at home. Explain why dihybrid boxes total sixteen.
Linkage, Crossing Over and X-Linked Traits
Part of: Linked Travel
Same-chromosome genes travel together, as Bateson-Punnett sweet peas and Morgan 1910 flies showed with 83 parental to 17 new; one per cent equals one map unit. White eyes ride X chromosomes to sons, plastids ride eggs to all children, and maize 1931 proved physical exchange.
Why it matters. 83-17 splits plus X-paths answer linkage questions.
Key words
- Linkage
- : Joint travel of genes.
- Crossing over
- : Segment exchange between homologues.
- Recombinant
- : New non-parental combination.
- Map unit
- : One per cent recombination distance.
- X-linked
- : Gene riding X chromosome.
- Maternal inheritance
- : Egg-only trait passage.
Try it in two minutes
- Travel same-chromosome genes.
- Split 83 from 17.
- Ride X to sons.
Try at home. Explain why linked genes still make some new combos.
Ploidy and Reverse Genetics
Part of: Sets and Direction
Triploids hold 3 sets through octoploids with 8, aneuploids miss or add single chromosomes, and crops prove counts: cotton 52 over 13 is tetraploid, wheat 42 over 7 hexaploid. Forward genetics starts phenotypes, reverse starts sequences using RNAi silencing.
Why it matters. Set division plus direction contrast answers genome questions.
Key words
- Ploidy
- : Number of chromosome sets.
- Aneuploidy
- : Missing or extra singles.
- Forward genetics
- : Phenotype-first gene hunt.
- Reverse genetics
- : Sequence-first function hunt.
- RNAi
- : Double-RNA gene silencing.
- Genome
- : One full chromosome set.
Try it in two minutes
- Divide total by set.
- Miss or add singles.
- Start phenotype or sequence.
Try at home. Explain why polyploids grow larger parts.
What your child will practise
- Linkage, Crossing Over and X-Linked Traits: Jungle Puzzle (Clue Puzzle)
- Linkage, Crossing Over and X-Linked Traits: Jungle Quick Fire (Quick Fire)
- Mendel's Laws: Candy Puzzle (Clue Puzzle)
- More Patterns: Ocean Quest (Flip and Match)
- Ploidy and Reverse Genetics: Space Quick Fire (Quick Fire)
- Quiz: Linkage, Crossing Over and X-Linked Traits (8 questions)
- Quiz: Mendel's Laws (8 questions)
- Quiz: More Patterns (8 questions)
- Quiz: Ploidy and Reverse Genetics (8 questions)