B7: Inheritance, variation & Evolution Flashcards
When are mutations able to happen?
When cells divide
What happens when a mutation happens at meiosis?
It completely changes changes the genetics of the gametes
What are the 4 genetically different gametes produced during sexual reproduction called?
Haploid cells
Which is the processes that results in the formation of two genetically identical daughter cells?
Mitosis
Sexual reproduction [definition]:
The process of reproduction where the nuclei of two gametes (sex cells) fuse to form a zygote
How many parents are involved in sexual reproduction?
2
Asexual Reproduction [definition]:
Asexual reproduction is the process of reproduction that forms genetically identical offspring from only one parent
Genome [definition]:
The genome is the entire (all) genetic material of an organism
What are the 3 levels of organisation in a genome?
- DNA
- Genes
- Chromosomes
Asexual reproduction in fungi [7]:
- Spores germinate form new fungus
- Hyphae from two different fungi join
- Zygote formed when nuclei has 2 sets of chromosomes
- Meiosis happens
- Spores w/ single set of chromosomes germinate to form new fungus
- Fungal hyphae contain nuclei with one set of chromosomes
- Mitosis
Hyphae [definition]:
A mass of thin threads that make up fungi
Where are the organs for sexual reproduction in plants and what are they? [2]:
- The flower
- The pollen and egg cells
Sexual Reproduction in plants [3]:
- The pollen from one flower must reach the female parts of another flower
- This is called pollination, it is the plant equivalent of mating
- Once the pollen has fused with the egg cell, seeds are formed
How are flowers adapted for pollination?
They are adapted to attract animal pollinators such as insects, birds, or bats
What does sexual reproduction bring about?
It introduces variation and enables plants to survive as conditions change through natural selection
What is the main disadvantage of asexual reproduction in plants?
The new plants are identical to their parent and so no variation is introduced
Reproduction in malaria inside the parasites
-
Where do malarial parasites reproduce asexually?
They reproduce asexually in the human liver and blood cells
What triggers the sexual reproduction of the malaria parasites?
The drop in temperature between the human body and the mosquito
What does the fast changing variation in malaria parasites cause?
The fast changing variation in malaria parasites results from a life cycle that includes mitosis alone in humans and a combination of meiosis and mitosis in the body of the female mosquito
Why does one always inherit their mitochondria DNA from their mother?
Because it comes from the mitochondria in the egg cell
What is the aim of the 100,000 genomes project?
To find out as much as possible about human DNA
What is a mutation unable to cause?
The destruction of an organism
What happens when mutations take place non-coding DNA? [2]:
- It does not directly affect the phenotype
- However, variants in the non-coding DNA can affect which genes are switched on and switched off
How does inheritance work? [4]:
- The chromosomes you inherit carry genetic information in the form of genes
- Many of these genes have different forms or alleles
- Each allele codes for a different protein
- The combination of alleles you inherit will determine your characteristics
Variation [definition]:
Within a population, variation describes differences in the characteristics of individuals
What differences can variation be a result of? [3]:
- A combination of genetic and environmental causes
- The conditions in which the organism developed (environment)
- Genetics (inherited genes)
Evolution [definition]:
The gradual change of inherited characteristics of biological populations over time
When does speciation happen? [2]:
- When the average phenotypes of two populations have diverged so much that the two populations can no longer breed to produce fertile offspring
- Two different species have been formed
Speciation [definition]:
The process by which two species evolve from a single original species by natural selection
Why does speciation happen? [2]:
- It can happen as a result of evolution
- Natural mutations can create new alleles and two populations can begin to diverge
Natural selection [2]:
- Natural selection was proposed by Charles Darwin in 1859
- He theorised that all species evolved from simple life forms that first appeared on Earth more than three billion years ago
How does natural selection happen? [3]:
- Individuals possessing genes that make them better adapted to the environment will have a greater chance of survival.
- Individuals with the best chances of survival are the most likely to breed successfully (because they survive).
- The characteristics responsible for the increase in the likelihood of survival are more likely to be passed on to the next generation.