Root Words & Defintions
Diploid
Di- meaning two
Two complete sets of chromosomes > one from each parent
What are chromosomal abnormalities?
Changes in chromosome number or structure that can affect an organism’s development or health.
Incomplete Inheritance
Heterozygote shows blended phenotype (e.g., red flower × white flower = pink flower).
Identify the type of reproduction in which meiosis occurs.
Sexual Reproduction
State what the squares and circle represent in a Pedigree chart?
Males - Squares
Females - Circle
Monogenic
Mono meaning one, Genic meaning gene
What is a Karyotype?
Karyotype is an organised visual display of an organism’s chromosomes
Identify which mechanism of inheritance is associated with cystic fibrosis?
Cystic fibrosis is associated with an autosomal recessive mechanism of inheritance.
How many products are formed at the end of meiosis? What are they called?
Meiosis produces four haploid gametes (daughter cells)
State a few factors that contribute to genetic diversity.
Mutations, Independent Assortment, Crossing over
Polyploidy
Ploy- meaning many, Ploidy- meaning the number of sets of chromosomes in a cell
Polyploidy is a condition where an organism has more than two complete sets of chromosomes in its cells
What is a homologous chromosome, and why are they important in meiosis?
Homologous chromosomes are pairs of chromosomes with the same genes but possibly different alleles. They allow proper segregation and crossing over during meiosis, increasing genetic diversity.
Two heterozygous parents (Aa × Aa) have offspring. State the genotypic Ratio. How does this Punnett square illustrate the potential for genetic diversity?
The offspring have a 1:2:1 genotypic ratio (AA:Aa:aa), showing different possible allele combinations even from the same parents, creating variation in genotypes and phenotypes.
What is the separation of homologous chromosomes (segregation)?
This specific event during meiosis I ensures that each gamete receives only one allele of each gene.
What is a monohybrid cross?
This type of cross examines the inheritance of a single trait between two parents.
Cytokinesis
Kinesis meaning movement
The process where the cytoplasm of a parent cell divides, forming two separate daughter cells
A chromosome where the centromere is not central and is instead located near the end of the chromosome.
Acrocentric
Why do mutations in gametes affect genetic diversity more than mutations in somatic cells?
Mutations in gametes affect genetic diversity because they are heritable and can be passed to offspring, while somatic mutations only affect the individual and do not influence the gene pool.
Describe nondisjunction
When chromosomes fail to separate properly during meiosis, it can lead to this type of chromosomal abnormality.
Two populations of the same species live in different environments. One has a higher mutation rate. Predict how this might affect the populations over time.
The population with higher mutation rates may develop more genetic variation, potentially allowing faster adaptation to environmental changes.
Submetacentric
Sub- meaning below, meta- meaning middle, centric meaning centre
A submetacentric chromosome is a chromosome whose centromere is slightly off-centre, closer to one end.
How does the structure of chromosomes help ensure accurate segregation during mitosis and meiosis?
The centromere and spindle fibers attach to chromatids to pull them apart precisely, preventing errors like nondisjunction.
How can polygenic inheritance explain the continuous variation seen in traits like height or skin colour?
Multiple genes contribute to a single trait, each with small effects, producing a range of phenotypes rather than discrete categories.
State and describe two processes within meiosis that increases genetic diversity
Crossing over -Homologous chromosomes pair up (synapsis) and exchange segments of chromatids.
Independent Assortment - Homologous chromosome pairs line up randomly at the cell’s equator.
Why do gametes need to be haploid for sexual reproduction to maintain the correct chromosome number?
Fertilization combines two haploid cells, restoring the diploid number in the zygote. Without haploid gametes, chromosome numbers would double each generation.