Genetics and Reproduction Flashcards
The differences in characteristics between individuals of the samespeciesis known as….
Variation
What type of variation is passed on from parents to offspring, via genes during reproduction
Genetic
Variation which is the result of differences in the surroundings, or what an individual does.
Environmental
Give three examples of genetic variation
blood group, natural skin colour and natural eye colour, free or attached earlobes (there are more - check your Science booklet for examples)
Give three examples of environmental variation
Scars, tattoos, hair length (there are more - check your Science booklet for examples)
How do you know blood group is a genetic (inherited) and not environmental characteristic?
You are born with a particular blood group
It cannot change during your life
Your lifestyle does not affect your blood group
In which part of the cell is genetic information found?
Nucleus
How many pairs of chromosomes do (most) human cells contain
23
What are chromosomes made of?
DNA (a long molecule)
A short section of DNA that codes for specific features is known as what?
Gene
How do we describe the structure of DNA?
Double helix
How many versions of each gene do we have?
2
What are different versions of the same gene known as?
Alleles
A person has genotype Hh - which letter represents the dominant allele and which represents the recessive allele
H - dominant. h - recessive
In cats - H represents long hair and h short hair. Cat 1 has genotype Hh, cat 2 also has genotype Hh - what is the chance their offspring will have short hair?
25% - possible combinations are HH (long hair), Hh (long hair), hH (long hair), hh (short hair) - you can use a punnet square to work this out
Rosalind Franklin is a famous scientist - what is she best known for?
Her research leading to the discovery of the structure of DNA
Name the scientists who won the Nobel prize for the discovery of the structure of DNA
James Watson, Francis Crick and Maurice Wilkins
What is 1?
Fallopian tube/oviduct
What is the purpose of the fallopian tube?
Transport the egg from the ovary to the uterus
What kind of cells are found in the fallopian tube that help the egg move through it?
Ciliated cells/cilia
What is 2?
Ovary
What is the purpose of the ovary?
Stores and releases egg cells
What is 3?
Cervix
What is the cervix?
This is a narrow opening between the vagina and uterus
What is 4?
Uterus
In which part of the female reproductive system does a foetus develop?
Uterus
What is 5?
Vagina
What is 1?
Scrotum
What is 2?
Penis
What is 3?
Urethra
What fluid/s can be transported in a male urethra?
Urine or semen
What fluid/s can be transported in a female urethra?
Urine only
What is the purpose of the glands (part 4?)
Add fluid to the sperm to make semen. The fluid provides nutrition for the sperm to give it the energy it requires to swim
What is 6?
Sperm duct
What is 7?
Testis (2 are called testes)
What is the purpose of the testes?
Production of sperm
What hormone is produced by the testes?
Testosterone
What hormones are produced by the ovaries?
Oestrogen and progesterone
Why are the testes outside of the body?
Lower temperature is better for sperm production
What is the period of life called between childhood and adulthood
Adolescence
What is puberty?
the period during which adolescents reach sexual maturity and become capable of reproduction.
What controls the changes that happen during puberty?
Hormones (in males - testosterone, in females - oestrogen and progesterone)
Give 3 examples of male changes during puberty
voice breaks, hair grows on face and body, body becomes more muscular, testes start to produce sperm, pubic and underarm hair grows, sexual organs grow and develop
Give 3 examples of female changes during puberty
pubic and underarm hair grows, sexual organs grow and develop, voice deepens gradually, hips get wider, breasts develop, menstruation starts
The menstrual cycle is approximately how many days long?
28
What happens on the first day of the menstrual cycle?
Menstruation (period) starts
What is menstruation (a period)?
The lining of the uterus comes away and exits through the vagina as blood.
What is ovulation?
When an egg is released by an ovary into the oviduct.
Approximately when during the menstrual cycle does ovulation occur?
Middle of the cycle (day 14)
What happens to the lining of the uterus if the egg is not fertilised?
It breaks down
What happens to the lining of the uterus if the egg is fertilised?
It does not break down
What is sexual reproduction?
The process of bringing together the egg and the sperm
What is fertilisation?
The process in which the nucleus of a sperm cell joins with the nucleus of an egg cell
Describe the journey of the sperm through the male and female reproductive system (list the parts it must pass through)
Testis - sperm duct - male urethra - penis - vagina - cervix - uterus - oviduct
Describe 2 sperm adaptations that help it perform its function
Tail - helps them swim to the egg.
Mitochondria - helps give the sperm energy.
Digestive enzymes - help the sperm penetrate the egg cell membrane.
Streamlined shape - help the sperm break down the egg’s outer layer.
Describe egg adaptations that help it perform its function (fertilisation)
Jelly coating- helps by only letting in one sperm.
Nutrients - act as a food source for the developing foetus.
How do non-identical twins occur?
How do identical twins occur?
What do we call the period of foetel development from conception to birth?
Gestation
What is formed when the sperm nucleus fuses with the egg nucleus?
Zygote
After cell division, what does a zygote then form?
Embryo
After further cell division, what does an embryo become?
Foetus
How long is the human gestation period?
40 weeks
What are 2 functions of the placenta
Provide nutrients (food and water) to the developing foetus
Provide oxygen to the developing foetus (for respiration)
Waste substance (e.g. carbon dioxide) removal.
Where is testosterone produced?
In the testes
