Genetics and Evolution Flashcards
Explain the functions of the female reproductive system
Uterus: Where menstruation takes place and baby grows.
Cervix: Ring of muscle at the entry of the uterus
Ovaries: Eggs are made here
Oviducts: Carries eggs from ovary to uterus, fertilisation occurs here.
Vagina: Entry to uterus.
Explain the functions of the male reproductive system
Scrotum: A bag of skin that protects and helps heat the testes.
Testes: Sperm is made here
Sperm ducts: Carries sperm from testes to penis.
Prostate gland:
Urethra: Also carries sperm out of the body.
Penis: Carries sperm out of the body.
State what gametes are and what happens during fertilisation
Gametes are reproductive and sex cells. During fertilisation the male and female gametes fuse together and create a zygote (egg).
Briefly describe the development from a zygote to an embryo and then a foetus
A zygote splits into an embryo and placenta, the embryo then develops into a foetus 8 weeks after.
Describe haploid and diploid cells
Haploid:
- Contains one set of chromosomes (n)
- Goes through the process of meiosis
- Example: gametes
Diploid:
- Contains two sets of chromosomes (2n)
- Goes through the process of mitosis.
- Example: skin and blood cells
Show the link between chromosomes, DNA and genes
Chromosomes carry DNA in cells. DNA is responsible for building and maintaining your human structure. Genes are segments of your DNA, which give you physical characteristics that make you unique
State the location of DNA/genes in a cell
DNA and genes are located in the cell nucleus.
Give a brief description of DNA (including double helix, and base pairs)
Known as a double helix, DNA is made up of simple repeating units called nucleotides. The nucleotides are comprised of a sugar, a phosphate and a base. They have complementary base pairings, such as adenine pairs with thymine (curved) and cytosine with guanine (straight).
Explain what the human genome is
The genome isthe entire set of DNA instructions found in a cell.
What does DNA stand for
Deoxyribonucleic acid
Explain the importance of DNA making exact copies of itself
Cells must replicate their DNA before they can divide. Thisensures that each daughter cell gets a copy of the genome, and therefore, successful inheritance of genetic traits.
What is mutation
Mutation is a change in genetic code
Give examples of mutations
Alzheimers disease, cystic fibrosis
List the causes of mutations
Mutations can result fromerrors in DNA replication during cell division, exposure to mutagens or a viral infection.
Give examples of how mutations can be useful or harmful
Useful:
- Essential for evolution
- Increase an organism’s changes of surviving or reproducing
- Becomes more common over time
Harmful:
- May cause genetic disorders or cancer
- frameshift mutation; the deletion or insertion of a sequence
Define genotype and phenotype
Genotype: the genetic makeup of an organism, an organism’s complete set of genes.
Phenotype: an individual’s observable traits (e.g eyes, height etc), which can both be by their genotype or environmental factors.
What do all cells except for gametes have
All cells except gametes have 2 genes/alleles for each characteristic.
Explain the difference between dominant and recessive genes / alleles
Dominant genes: The gene physically expressed that overshadows recessive.
Recessive genes: The gene not expressed because of the dominant gene.
State what variation is and what causes it
Variation is any difference between cells, individual organisms, or groups of organisms caused bygenetic differences (genotypic variation) or effect of environmental factors (phenotypic variation).
Describe the 2 types of variation
Continuous: A complete range of measurements from one extreme to the other.
e.g height, weight
Discrete: when characteristics fall into a number of distinct categories.
e.g attached vs detached earlobes, finger prints, eye colour, and blood groups
Describe mitosis
(normal cell division)
The process of a cell replicating its chromosomes and then segregating them, producing two identical nuclei in preparation for cell division. They are genetically identical.
Describe meiosis
Cell division in sexually reproducing organisms that reduces the number of chromosomes in gametes (sex cells).
Explain the difference between haploid and diploid cells with examples
Haploid:
- Contains one set of chromosomes (n)
- Goes through the process of meiosis
- Example: gametes
Diploid:
- Contains two sets of chromosomes (2n)
- Goes through the process of mitosis.
- Example: skin and blood cells
Define evolution
The process of species adapting over time due to the changing environment.
Explain selective breeding and give examples
Choosing parents with particular characteristics to breed and produce offspring with those characteristics.
eg race horses
Discuss Darwin’s idea of evolution by natural selection
Darwin’s idea of evolution by natural selection believed in the survival of the fittest. Individuals genetically better suited to the environment will survive longer and therefore product more offspring. Therefore passing on their genes and making them more common.
Explain the importance of variation as a key feature of natural selection
Variation is key as between the animals/plant etc, the better adapted survivors will pass on their better genes to their offspring who will also show this beneficial variation.
Explain what evolution led to
diversification of species like a tree, not a ladder
Define the term fitness in the context of natural selection
Any feature that helps a creature live and breed to become more numerous.
Explain the meaning of ‘scientific theory’
explanation of an aspect of the natural world and universe that can be repeatedly tested
Discuss evidence that supports the theory of evolution
All species of life have evolved over time from one or a few common ancestors through the process of natural selection.
Label diagrams of the male and female reproductive organs
Describe heterozygous and homozygous
Heterozygous: For a particular characteristic or ‘allele’ it is made up of 2 different genes.
- example: tall, Tt, tT
Homozygous: The two genes for a particular characteristic is the same.
- example: tall, TT, tt
What is a zygote
A fertilised egg cell
