Evolution
7th Grade Science · 15 lessons
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Lessons
- 1What Are Chromosomes?Chromosomes are structures made of tightly coiled DNA and proteins. Human body cells have 46 chromosomes (23 pairs), while sex cells have 23 chromosomes.Lesson
- 2Meiosis and Sex CellsMeiosis is a special type of cell division that produces sex cells (gametes) with half the normal number of chromosomes. When egg and sperm unite, the full number is restored.Experiment
- 3Dominant and Recessive AllelesDominant alleles are expressed when present, while recessive alleles are only expressed when two copies are present. A person with one dominant and one recessive allele shows the dominant trait.Lesson
- 4Genetic VariationGenetic variation within a population is essential for evolution. Variation comes from mutations, sexual reproduction, and gene flow between populations.Lesson
- 5Punnett SquaresPunnett squares are tools for predicting the probability of offspring inheriting particular traits. They show all possible combinations of alleles from two parents.Experiment
- 6Cell Organelles and Their JobsCell organelles each have specific functions. The mitochondria produce energy, the ribosome makes proteins, the endoplasmic reticulum processes molecules, and the Golgi apparatus packages them.Lesson
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