Question | Answer |
What is a gamete? | A haploid cell (sex cell) |
What are animal gametes called? | sperm (male) and egg (female) |
What are plant gametes called? | pollen (male) and ovule (female) |
What animal structure produces sperm? | testes |
What animal structure produces eggs? | ovary |
What plant structure produces pollen? | anther |
What plant structure produces ovules? | ovary |
What is a zygote? | A fertilised egg |
What is a chromosome complement of a cell? | A total number of chromosomes that a cell contains. |
What is a chromosome complement of a human diploid cell | 46 chromosomes |
What is a chromosome complement of a human gamete (haploid cell)? | 23 chromosomes |
What are haploid cells? | Cells that have exactly half of the chromosome complement of a diploid cell |
Is a zygote a diploid or a haploid cell? | Diploid |
Why is a zygote a diploid cell? | because it is made from two haploid cells whose nuclei have fused at fertilisation |
What is a phenotype? | An outward appearance of an organism, eg. blue eyes |
What is a genotype? | A combination of alleles that organism has for a given characteristic eg. Bb, BB, or bb |
What is a heterozygous genotype? | two different alleles, Bb |
What is a homozygous genotype? | two same alleles, BB or bb |
Example of a homozygous dominant genotype | BB |
Example of a homozygous recessive genotype | bb |
What is polygenic inheritance? | Inheritance of characteristics that are controlled by more than one gene. eg. height |
What kind of variation does polygenic inheritance lead to? | continuous variation |
What kind of variation is seen when characteristic is controlled by a single gene? | discrete variation |
Name two examples of continuous variation | height, hand span |
Name two examples of discrete variation | blood type, eye colour |
What is discrete variation? | variation in which individuals can be divided into discrete groups |
What is continuous variation? | variation in which individuals vary along a continuum. Needs to be measured (has units) |
What is an allele? | A version of a gene |
How do new alleles appear? | by mutation |
Why does actual offspring ration sometimes differ from predicted ratio in genetic crosses? | when number of offspring is small sometimes ratios differ from predicted due to chance |