1. Trilogy – Biology – CHAPTER 6 – Genetics
What is a gene?
Sexual reproduction involves the joining (fusion) of male and female g__________ (sperm and egg cells in animals).
In sexual reproduction there is mixing of g___________information, which leads to v__________ in the offspring.
The formation of gametes involves cell division called m___________.
The genetic material in the nucleus of a cell is composed of a chemical called D____contained in the c___________
Human body cells contain __________ pairs of chromosomes.
DNA is made of very large molecules in long strands, twisted to form a d_______ h________.
A g________ is a small section of DNA on a chromosome.
All the genetic material of an individual is called its g____________
What is an allele?
If an individual is heterozygous, what can you say about their two alleles?
Cystic fibrosis is caused by a recessive allele.
Using N to represent the normal dominant allele and n to
represent the cystic fibrosis allele, answer the following questions.
A Complete this diagram to show what the possible genotypes would be if two parents, both of genotype Nn, had children. X Y
An embryo is formed from the two gametes above.
Will it be male or female? ______________
What type of cell division produces gametes? _______________
How many daughter cells are produced by this type of cell division? ______
Male
Gametes N n
Female
B What percentage of the children would have the disease? __________
C A ‘carrier’ is someone who does not have a genetic disease but whose cells contain one allele for the disease. What percentage of the children would be carriers? _______________
KEY WORDS:
Gene allele dominant recessive chromosome DNA homozygous heterozygous Double helix
ASSESSMENT:

2. Trilogy – Biology – CHAPTER 6 – Genetics
What are clones?
Advantages of sexual reproduction 1 2
Advantages of asexual reproduction
What type of reproduction produces clones?
Name an organism that reproduces both sexually and asexually?
In this genetic diagram, the gene for a genetic condition called Huntington’s is dominant.
What is the phenotype of the mother?
What is the phenotype of the father?
What percentage of their children are likely to inherit the condition?
What is the name of this type of diagram?
What is it used for?
What is embryo screening?
Give an example of a potential social problem associated with embryo screening.

3. Trilogy – Biology – CHAPTER 6 – Genetics
What is a gene? Part of a chromosome that codes for a protein ( controls a characteristic)
Sexual reproduction involves the joining (fusion) of male and female gametes (sperm and egg cells in animals).
In sexual reproduction there is mixing of genetic_information, which leads to variation in the offspring.
The formation of gametes involves cell division called meiosis.
The genetic material in the nucleus of a cell is composed of a chemical called DNA_contained in the chromosomes
Human body cells contain 23 pairs of chromosomes.
DNA is made of very large molecules in long strands, twisted to form a double helix.
A gene is a small section of DNA on a chromosome.
All the genetic material of an individual is called its genome.
What is an allele? One version of a gene
If an individual is heterozygous, what can you say about their two alleles? They are different.
Cystic fibrosis is caused by a recessive allele.
Using N to represent the normal dominant allele and n to
represent the cystic fibrosis allele, answer the following questions.
A Complete this diagram to show what the possible genotypes would be if two parents, both of genotype Nn, had children. X Y
An embryo is formed from the two gametes above.
Will it be male or female? ___male_____
What type of cell division produces gametes? __meiosis___
How many daughter cells are produced by this type of cell division? __4__
Male
Gametes N n
Female
 NN
 Nn
Nn 
 nn
B What percentage of the children would have the disease? ____25%______
C A ‘carrier’ is someone who does not have a genetic disease but whose cells contain one allele for the disease. What percentage of the children would be carriers? __50%_______
KEY WORDS:
Gene allele dominant recessive chromosome DNA homozygous heterozygous Double helix
ASSESSMENT:

4. Trilogy – Biology – CHAPTER 6 – Genetics
What are clones? Genetically identical copies
Advantages of sexual reproduction
1 Produces variation in the offspring.
2 Offspring can survive a wider range of environmental conditions/ diseases.
Advantages of asexual reproduction
1 Produces large numbers very quickly.
2 Can take advantage of good conditions or food sources.
What type of reproduction produces clones? Asexual reproduction
Name an organism that reproduces both sexually and asexually? A flowering plant like a strawberry. Aphids.
In this genetic diagram, the gene for a genetic condition called Huntington’s is dominant.
What is the phenotype of the mother? Suffers from the disease
What is the phenotype of the father? Does not have the disease.
What percentage of their children are likely to inherit the condition? 50%
What is the name of this type of diagram? Family tree for pedigree analysis
What is it used for? Working out the chance of inheriting a condition
What is embryo screening? Testing embryos for genetic diseases
Give an example of a potential social problem associated with embryo screening. People could choose the sex of their babies and lead to an imbalance in numbers.