B6- Inheritance, Variation and Evolution (P2) Flashcards
How many chromosomes do human gametes have
23
What type of cell division are gametes made from
Meiosis
What’s the result of cell division by meiosis
Non-identical cells
What are the gametes in flowering plants
Pollen and egg cells
What type of reproduction do animals and plants carry out
Sexual reproduction
What is sexual reproduction
The fusion of male and female gametes and also involving the mixing of genetic information
What does sexual reproduction allow
Variation in the offspring
Describe asexual reproduction
There is one parent so no mixing of genetic information therefore offspring are genetically identical
Where does meiosis take place
Reproductive organs
What is the reproductive organs in a male
Testes
What is the reproductive organ in a female
Ovaries
What’s the first stage of meiosis
All of the chromosomes are copied
What’s the second stage of meiosis 
The cell divides into two
What’s the third stage of meiosis
Both cells produce divide once more to produce gametes
After fertilisation how many chromosomes does the embryo have
46
How does an embryo divide
By mitosis
Why does an embryo divide by mitosis
To produce identical cells
What are the advantages of sexual reproduction
There’s a survival advantage by natural selection
Greater chance of survival in challenging conditions
What are the advantages of asexual reproduction
Only one parent needed
Energy and time efficient
Faster
Useful in favourable conditions
What is the disadvantages of asexual reproduction
Risk offspring may die in conditions that become unfavourable 
What type of reproduction does the malaria parasite allow
Sexual and asexual reproduction
What type of reproduction does malaria parasite do in the human host
Asexual reproduction
Where does the malaria parasite use sexual reproduction
In the mosquito
How do fungi reproduce asexually
By producing spores
Why do plants reproduce sexually
To produce seeds
How do plants reproduce asexually
Sending out runners
How do daffodils reproduce asexually
Through bulb division
What’s the structure of DNA
A polymer of molecules called nucleotides
How many structures do nucleotides have
Three main structures
What are the three main structures of nucleotides
A phosphate group, sugar molecule and base
Which of the three Structures of nucleotides change
The base
How many possible bases are there
Four
What’s the names of the four bases
A,C,G,T
Why are DNA strands complimentary
The same bases always pair on the opposite strands
The base C is always linked with what other base 
G
What is T linked with
A
How is the shape and function of a protein determined
By the order of amino acids
What determines the order of amino acids in a protein
The sequence of bases in the gene that code for the protein
What stage one of protein synthesis called
Transcription
Describe stage one of protein synthesis
The base sequence of the gene is copied into a complimentary template molecule called mRNA
What is stage two of protein synthesis called
Translation
Describe stage two of protein synthesis
The mRNA molecule attaches to a ribosome.
Amino acids are brought to the ribosome on carrier molecules.
The ribosome now reads the triplet of bases on the mRNA to join to gather correct amino acids in the right order.
What is a mutation
A change to a base
What changes the shape of a protein
If a mutation alters the amino acids
What happens if a mutation changes the shape of a structural protein
The protein may lose strength
What are alleles
Versions of a gene
What is genotype
The alleles present of a person
What is phenotype
The characteristics caused by alleles
What is homozygous
Two of the same alleles
What is heterozygous
Two different alleles
What is the dominant allele
Are you that will show in phenotype even if one copy is present
What is the Recessive allele
When both alleles are needed to show the phenotype
What is cystic fibrosis
The disorder of cell membranes
Is cystic fibrosis recessive or dominant
Recessive
What is polydactyly
An inherited disorder which causes extra toes or fingers
Is polydactyly caused by a dominant or recessive allele
Dominant
What is embryo screening
When embryos are tested to see if they have the alleles for inherited disorders
What’s the issues around embryo screening 
-expensive
-Large number of embryos are created but only a small number used
-People can choose desirable features which is unethical
What are family trees
They share the genetic history of a family history by showing the phenotype
What chromosome is the male sex chromosome
XY
What is a female sex chromosome
XX
What characteristic have dogs been selectively bred for
Gentle nature
What characteristic have food crops Been selectively bred for
To have disease resistance
What characteristic have cows been selectively bred for
To produce more milk and meat
What characteristic have plants been selectively bred for
A larger flower
What is the first step in selective breeding
From a mixed population of species select the males and females who have the desired trait
What is step two in selective breeding
Breed the male and female together to produce offspring
What’s the third step in selective breeding
Select the offspring that carry the desired trait and breed them together
What is step four in selective breading
Continue breeding offspring for generations until all the offspring carry the desired trait
What are the disadvantages of selective breeding
Breeding close relatives can result in inbreeding which can cause breeds to be prone to disease or inherited defects
What is genetic engineering
When genes of an organism are cut out and transferred to a cell of a different organism
What can genetically modified crops produce
Higher yield
Resistance to disease
Resistance to insect attacks
Resistance to herbicides
Produce bigger or better food
What is step one in genetic engineering
Identify the gene you want to transfer
What is STEP2 in genetic engineering
Use enzymes to isolate the gene
What is step three in genetic engineering
Transfer the gene into a small circle of DNA called a plasmid
What is step 4 in genetic engineering
Transfer the desired gene into the cells of the target organism
Why does the transfer of the gene have to occur at an early stage
To make sure all the cells receive the transferred gene
How do you take cuttings for plant cloning
Remove a small piece of the plant and dip the end in rooting powder
What’s the purpose of using rooting powder when taking cuttings
It contains plant hormones which encourages the plant to develop roots 
What’s the stages for tissue culture
Take a plant you want to clone and divide it into hundreds of tiny pieces
Incubate the cells with plant hormones to stimulate growth
What must the conditions be for tissue culture
Sterile 
What is tissue culture useful for
Cloning hundreds of plants
To preserve rare species of plants
What’s the first stage in embryo transplant
Select the sperm and egg cells from the animals with the desired characteristics
What is a step two in cloning by embryo transplant
Allow for fertilisation to take place to produce an early stage embryo
What is stage three in cloning by embryo transplant
Use a glass rod to split the embryos into two
What is stage four in cloning by embryo transplant
Transplant the embryos into the hosts mother
What is stage five in embryo transplant cloning
The embryos will develop into two identical offspring
What is the disadvantage of embryo transplant
There will be variation in the offspring so the desired characteristics may not appear in the offspring 
What is the advantage of adult cell cloning
It allows for the characteristics desired to be produced
What is stage one in adult cell cleaning
Remove the cell that you want to clone
What is stage two in adult cell cloning
Remove the nucleus from the cell
What is stage three in adult cell cloning
Take an unfertilised egg cell from the same species and remove the nucleus
What is stage four in adult cell cloning
Insert nucleus from original cell into the egg cell
What is stage five in adult cell cloning
Give the egg cell an electric shock so it divides to form an embryo
What is stage six in adult cell cloning
Insert embryo into the womb of an adult female
How did Darwin develop his theory of evolution (s)
Through many years of experimentation
How are organisms more likely to breed successfully (s)
Through having characteristics that are more suited to the environment and which allow them to survive
What was the name of Darwin’s book and when was it published (s)
Darwin published ‘on the origin of species’ in 1859
Why was Darwins theory controversial (s)
Because many people believed God created everything on the Earth and Darwin’s theory challenged this
What did Lamarck suggest (s)
When the characteristic is regularly used it becomes more developed. The strength and characteristic is then passed onto The Offspring
Why was Lamarcks theory incorrect (s)
Because changes to a characteristic in an organisms lifetime cannot be inherited
Which two scientists proposed a similar theory of speciation together in 1858 (s)
Darwin and Wallace
What is speciation (s)
The process of how new species form
What is the first stage of speciation (s)
A geographical barrier splits the population of a species into two
What is stage two of speciation (s)
The barrier prevents interbreeding between the two populations
What is stage three of speciation (s)
Overtime, natural selection will favour different alleles between the two populations
What is stage four of speciation (s)
Any mutations that occur cannot spread between the two populations because the two populations don’t interbreed
What is stage five of speciation (s)
The mutations causes the species to change
What is stage six of speciation (s)
If the population mix again any breeding That occurs between the two populations will cause infertile offspring because they are two different species
What does speciation require (s)
A geographical barrier
Who is the cause of our understanding of genetics (s)
Gregor Mendel
What did Mandel carry out experiments on (s)
The breeding of pea plants in the 1800s
In the 1800s what was the general idea around inheritance of characteristics amongst scientists (s)
Many scientists believe characteristics were blended when they were inherited
What were Mendel’s discoveries (s)
Characteristics were determined by inherited units and that they could be masked and then reappear in later generations
What are fossils 
The remains of organisms from millions of years ago which are found in rocks
What’s the first way fossils can be formed
When parts of organisms have not decayed this happens when conditions needed for decay are absent
What is the second way fossils can be formed
When an organism is slowly replaced by minerals during the decay process
What’s the third way fossils can be formed 
Fossils can be the preserved traces of organisms for example footprints
Why is it difficult to trace back early life
Many early life organisms were softbodied meaning they didn’t contain a skeleton or shell. This has caused the fossils to have been destroyed by the earths crust
What is the reasons why species have become extinct
Catastrophic events
Environment changes
New diseases
New predators
The evolution of more successful species
In ideal conditions how long does it take for bacteria to reproduce
Every 30 minutes
What does the fast rate of reproduction allow bacteria to do
Evolve rapidly
Why are some strains of bacteria no longer killed by antibiotics
Because bacteria have evolved and some are now antibiotic resistant
What is a common strain of antibiotic resistant bacteria
MRSA
What is the first stage of antibiotic resistance
Antibiotic resistant bacteria occur due to mutation
What is stage 2 of antibiotic resistance
Antibiotics used to kill bacteria will not kill the resistant bacterium
What is stage 3 in antibiotic resistance
This allows for the antibiotic resistant strain to survive and reproduce without any competition
How can antibiotic resistant bacteria decrease
- antibiotics shouldn’t be prescribed inappropriately
- Patients should complete their full course of antibiotics
- Reduce use of antibiotics in farming
Who began to classify species into categories based on structure and characteristics
Carl Linnaeus in the 1700s
What did Linneaus divide all living organisms into
Two kingdoms : Plant and animal kingdom
What were the smaller categories Lennaeus divided each kingdoms into
Kingdom -> Phylum -> Class -> Order -> Family -> Genus -> Species
How is an organism named
By their Genus then species
What is the name of the system of how organisms are named
The binomial system
Who came up with the ‘three domain’ system
Carl Woese
What does the three domains system include
Archae
True bacteria
Eukaryota
What shows the relations between organisms
Evolutionary trees
What do evolutionary trees show
Common ancestors
