GCSE Biology: Inheritance & Evolution — Quick Burst Practice

Inside GCSE Biology: Inheritance & Evolution — Quick Burst Practice

name DNA, genes and chromosomes, nail the genetic terms (homozygous, phenotype, recessive), work fresh monohybrid crosses and read off ratios and percentages, decide sex from XX and XY, then recall natural selection, selective breeding and genetic engineering. About 10 minutes.

Learning objectives

• the molecules of inheritance — naming DNA, genes and chromosomes;
• genetic vocabulary — homozygous and heterozygous, genotype and phenotype, dominant and recessive;
• monohybrid crosses — reading genotypes, phenotype ratios and percentages from fresh TT × tt and Tt × tt crosses;
• sex determination and evolution — XX/XY and probability, natural selection, selective breeding and genetic engineering.

Activities in this book

1. Round 1 — DNA, Genes & Chromosomes

   DNA is the molecule that carries the genetic code. A gene is a short section of DNA that codes for one protein. Chromosomes are long, coiled lengths of DNA found in the nucleus — humans have 23 pairs.

2. Round 2 — Genetic Terms Sprint

   two identical alleles (TT or tt) = homozygous; two different alleles (Tt) = heterozygous. The phenotype is the characteristic you can see; the genotype is the alleles behind it. A recessive allele only shows up when two copies are present.

3. Round 3 — Punnett Power Round

   take T = tall (dominant) and t = short (recessive). TT × tt gives all Tt offspring (all tall, all heterozygous). Tt × tt gives Tt, Tt, tt, tt — a 1:1 tall:short ratio, so half are short.

4. Round 4 — Sex Determination Blast

   sex is set by the sex chromosomes: XX is female, XY is male. An egg always carries an X; a sperm carries either an X or a Y. An XX × XY cross gives XX, XY, XX, XY, so boys and girls are equally likely.

5. Round 5 — Evolution Lightning Round

   natural selection: the best-adapted individuals survive and pass on their genes. Selective breeding is humans choosing which organisms breed for a wanted feature. Genetic engineering transfers a chosen gene from one organism into another.

Suggestions for teaching

• Keep it quick. Set a timer — the point of a quick burst is fluent recall, not extended working.
• Little and often. Use these rounds as a warm-up or exit ticket rather than a full lesson.
• Model one cross live. Draw the Tt × tt grid on the board so learners see why the ratio is 1:1 and short is 50%.