Inheritance, Variation, Evolution Flashcards
Describe asexual reproduction?
●One parent only
●No fusion of gametes so no mixing of genetic info
●Production of genetically identical offspring (clones)
●Mitosis
How do strawberry plants produce asexually?
Seed out long shoots called runners which touch the ground and grow a new plant
How do daffodils asexually reproduce?
Daffodils produce alot of smaller bulbs which grow into new plants
How does fungi asexually reproduce?
By spores
How does malarial protists reproduce asexually when they are in the human host
Do gardeners use asexual reproduction?
Yes, to produce large numbers of identical plants
What does sexual reproduction involve?
Fusion (joining) of male and female gametes:
●Sperm and egg cells in animals
●Pollen and egg cells in flowering plants
What does sexual reproduction create in terms of offspring?
The mix of genetic information produces variation in offspring
What process does the formation of gametes in sexual reproduction involve?
Meosis
Describe the process of meiosis?
1) Cells with two pairs of chromosomes (diploid cell)
2) Each chromosome replicates itself
3) Chromosomes part and move to opposite poles/sides
4) Cells divide for first time
5) Copies now separate and 2nd cell division takes place
6) Four haploid Cells (gametes) each with half thd number of chromosomes of the parent cell
What happens to a cell during meiosis?
●Copies of genetic info are made
●Cell divides twice to form four gametes with a single set of chromosomes
●All gametes are genetically different
Why is meiosis important?
Halves the number of chromosomes in gametes, so fertilisation can restore the full number of chromosomes, once fertilised the resulting egg divides rapidly by mitosis and cells become specialised
How many chromosomes are in a sperm and egg cells?
Contain single chromosomes (1 of each chromosome instead of the normal 2)
What part of the body does meosis take place in?
The reproductive organs (testes in males, ovaries in females)
What are some advantages of sexual reproduction?
●Produces offspring variation
●If environment changes, variation means some organisms will survive
●Selective breeding in plants and animals
●Increases food production
What are some advantages of asexual reproduction?
●Only one parent needed
●More time and energy efficient, don’t need to find a mate
●Faster than sexual
●Produced to make best use of good conditions
How do plants produce sexually and asexually?
●Produce seeds sexually (insects carry pollen from a male part to a female part)
●Reproduce asexually using bulbs and runners
How does malaria produce sexually and asexually ?
●Malaria produces sexually in mosquito
●Asexually in humans (multiplies continously on its own)
When organisms have a choice which sort of way to reproduce, what do they chose when conditions are good?
Asexually
When organisms have a choice which way to reproduce, what do they chose when conditions are getting worse?
Sexually, fir example when there is lack of food or drop in temp (they can’t keep reproducing on there own so find something else with some food so they can produce together as the don’t have enough energy on their own)
What does DNA contain?
Structures called chromosomes
What is a gene?
Small section if DNA on a chromosome
What does each gene code for?
A particular sequence of amino acids which make a specific protein
What is the genome?
All the genetic material found in an organism
Has whole genome been studied?
Yes, it has important uses for doctors and scientists
Now the whole genome has been studied how does this help doctors?
●Doctors can search for genes linked to different types of disorders
Now the whole genome has been studied how does this help scientists?
●Help scientists understand cause of inherited diseases and how to treat them
●scientists investigate how humans have changed over time
What is DNA made up of?
A polymer made up of repeating units called nucleotides
What does each nucleotide consists of?
●A sugar
●A phosphate
●One of the four bases: A,C,G or T
How are nucleotides joined together?
Joined together to form long strands
How does each nucleotide molecule make a double helix?
Each molecule has two alternating sugar and phosphate strands which are twisted to form a double helix, this is the outside of the double helix structure called the sugar phosphate backbone
What is attached to the sugar phosphate backbone?
One of the four bases
What three types of molecule make up DNA?
●Sugar
●Phosphate
●Base
What did Gregor Mendel discover?
That characteristics are determined by ‘units’ that are inherited and don’t blend together
Why was the importance of Mendels discovery not recognised?
●A monk so worked in a monastery not a scientist at uni
●Didn’t publish his work
Can some characteristics be controlled by a single gene?
Yes,
Give an example in humans and animals where characteristics are controlled by a single gene?
Fur colour in mice
Colour blindness in humans
What do many genes have?
Different forms called alleles (an alternative form of a particular gene)
What is an allele?
An alternative form of a particular gene
How many alleles does each person have?
Two alleles for each gene
A person has two alleles for each gene where do the alleles come from?
One alleles from mother
One allele from father
What is a genotype?
Combination of alleles in a gene. For example bb
What is phenotype?
How alleles are expressed (what characteristics appear)
What does a dominant allele do in terms of characteristics?
Dominant allele always expressed (even if only one copy is present)
What does a recessive allele do in terms of characteristics?
The allele is only expressed if two copies present (no dominant allele)
What does homozygous mean?
Two alleles present are the same. For example BB,bb
What is heterozygous?
Alleles are different. For example Bb
How many genes controll characteristics?
Many genes that work together
What is monohybrid inheritance?
When only one gene is involved
How can we predict monohybrid cross outcomes?
Genetic diagrams / punnet squares
What have scientists used fossils for?
To look at how organisms have changed over long time periods
Why are there gaps in fossil records?
●Many early forms were soft bodied so left very few traces behind
●Traces left may have been destroyed by geological activity (like earthquakes)
How can the development of antibiotic resistant bacteria be explained by the theory of natural selection?
■Bacteria can evolve rapidly dye to fast reproduction rate
■Mutatee bacteria can be resistant to antibiotics and not killed
■These bacteria survive and reproduce so resistant strain develops
What is a monohybrid cross?
Crosses of single gene combinations
How do genetic disorders occur?
Genetic disorders are inherited and caused by inheritance of certain alleles
How is polydactyl inherited?
Dominant allele
How is cystic fibrosis inherited?
Recessive allele
What is polydactyly?
Extra fingers or toes
What is cystic fibrosis?
A disorder of cell membranes
What are the female sex chromosomes?
XX
What sex chromosomes makes a male?
X and a shorter Y chromosome
What chromosomes do offspring inherit from mum and dad?
♡One sex chromosome from mum (X)
♡One sex chromosome from dad (X or Y)
What is variation?
Differences in characteristics of individuals in a population
Along with Dareins theory what else provides evidence for evolution?
Fossils
What are fossils?
Remains of organisms from hundreds of thousands of years ago found in rocks
Name the 4 ways fossils are formed?
●Hards parts of animals which don’t decay easily
●Parts of organisms that haven’t decayed due to more than one of the conditions needed for decay are absent
●Parts of organisms replaced by other materials as they decay
●Preserved traces of organisms like footprints
How is decay to form fossils of an organism affected by weather?
Parts of organisms that haven’t decayed due to more than one of the conditions needed for decay are absent
What is variation due to differences in?
-Genes inherited (genetics)
-Conditions individuals have developed in (environmental)
-Combination of both
What do mutations create?
New alleles
What happens when a mutation affects a phenotype?
Mutation may produce a phenotype that gives an organism a great survival advantage
Do mutations affect a phenotype?
No, but it happens very rarely
Define evolution?
The gradual change in inherited characteristics of a population over time,leads to a formation of a new species
What leads to a formation of a new species?
Evolution
What did Darwin observe in terms of offspring?
Organisms often produce large numbers of offspring
What did Darwin observe in terms of population size?
Populations usually stay about the sane size
What did Darwin observe in terms of differences?
Organisms are slightly different/ show variation
What did Darwin observe in terms of inheritance?
Characteristics are inherited
What did Darwin use his observations to conclude in terms of exsistence?
Struggle for exsistence
What did Darwin use his observations to conclude about organism survival?
More organism are born than can survive
What did Darwin use his observations to conclude about breeding?
The ones that survive and breed are the best suited to the environment
What did Darwins observations conclude about characteristics?
Organisms pass characteristics onto their offspring
What did Darwin use his observations to conclude about characteristic change?
Over long period of time, characteristics of populations change
What was the name of a man who came up with a similar idea to Darwin?
Alfred Russel Wallace
What did Wallaces theory make Darwin do?
Made Darwin realise to publish his findings
What was the name of Darwins book?
On the origin of species. Published in 1859
Why did it take people a while to accept Darwins theory?
-Challenged that God made all organisms on earth
-Not enough evidence to convince scientists
-Mechanisms (how it works) of inheritance and variation not known until 50 years after theory was published
What is lamarcks idea of how giraffes necks developed?
Lamarck=necks of giraffes stretched during their lifetime, this characteristic was passed on to next generation
What is Darsins idea of how giraffes necks developed?
Darwin=giraffes that had longer necks could reach more food in trees so more likely to survive and reproduce
Why are there only a few blood types?
Controlled by a single gene
Why is there a range of heights?
Height is a combination of genes and environment
Who was Lamarck?
Came up with another idea of evolution
What was Lamarcks theory of evolution?
Idea that changes occur in an organism during its lifetime can be inherited, know now that this inheritance can’t occur
What is a use of selective breeding in crops?
Produce food crops from wild plants
What is a use of selective breeding in animals?
Produce domesticated animals from wild animals
Define selective breeding?
Process by which humans breed plants and animals with particular, desirable characteristics
What is the first and second step of selective breeding?
1) Choose parents with best desired characteristics
2) Breed them together
What are the 3rd and 4th step of selective breeding?
3)From offspring choose those with desired characteristics and breed
4)Continue over generations
What are some characteristics that are selected for selective breeding?
☆Disease resistance in food crops
☆Animals that produce more milk or meat
☆Domestic dogs that are gentle
☆Large or unusual flowers
What can be a problem with selective breeding?
Can lead to inbreeding
What is inbreeding?
Where some breeds are prone to disease or inherited defects
What is genetic engineering?
Process of moving a gene from one organism to another
How are ways plants have already been already genetically engineered ?
•To be resistant to disease,insects,herbicide attack
•To produce bigger, better fruits
What is a herbicide attack?
Undesired effect due to coming in contact with a weed killer pesticide
What is the name given to crops that have had their genes modified?
Genetically modified (GM) crops
Concerns about GM crops?
*Long term effects on insects and wildflowers
*Genes for insect resistance may enter wild
*Effect on human health
How has genetically engineering been beneficial for humans?
Fungi/bacterial cells have been genetically engineered to produce insulin to treat type 1 diabetes
What are the 3 stages of producing genetically engineered insulin?
1-Human insulin gene taken from part of human chromosome
2-Ring of bacterial DNA (plasmid) cut open
3-Human insulin gene inserted into plasmid
Define clone?
Genetically identical
How are clones produced?
Asexually
How does cloning work with plants?
Produced from cuttings or tissue culture (small groups of cells to grow new plants)
What are the 5 steps of cloning?
1-Nucleus taken from skin cell of organism to be cloned
2-Nucleus inserted into egg cell
3-Electric shock causes cell to split and develop
4-Developing cells inserted into surrogate mother
5-Clone is born
What are the 4 stages to cloning a plant with cuttings?
1-Select plant
2-Take cuttings
3-Place cuttings in soil and dampness
4-Genetically identical plant devdlops
What are is Carl linneaus classification?
Kingdom
Phylum
Class
Order
Family
Genus
Species
How are organisms named?
By the binomial system
What is the binomial system?
Method of naming organism by using their genus and species
Give an example of the binomial system?
Name for lion is pathera leo and name for tiger is panthera tigris. Same genus different species
Define genus?
Group of closely related species
Why is there new models of classification?
●Microscope improvement
●Biochemical processes (how body converts food into energy etc) better understoood
What system had been developed due to evidence from genetic studies?
A three-domain system
Who developed the three-domain system?
Carl Woese
Who created classification?
Carl Linneaus
What 3 categories have organisms been divided into in the three-domain system?
Archae,bacteria,eukaryota
According to the three-domain system what is archae?
Primitive bacteria, live in extreme environments
According to three-domain system what is bacteria?
True bacteria, have flagella
According to the three-domain system what is eukaryota?
Protists,fungi,plants,animals
What are some causes of extinction?
☆Humans (over hunting)
☆Changes to environment
☆New predators
☆New disease
☆Catastrophic event (🦕🦖)
☆New,more successful competitors
What are evolutionary trees?
Method used by scientists to show how they think organisms are related
What do scientists use current classification data for?
For fossil data and living organisms to find out more about extinct organisms
What is speciation?
•Lowest level of classification system
•Members similar enough to breed and produce fertile offspring
What was another theory Alfred Russel Wallacs came up with other than evolution?
Speciation-how species develop
What is speciation?
How species develop
What are the 4 stages of speciation by Alfred Russel Wallace?
1)populations become physically isolated from each other e.g ocean
2)genetic variation
3)natural selection is different in the two species
4)populations become so different that they can’t breed
How do scientists know that two organisms have become different species?
They can no longer breed
What does the name felis catus for domestic cats tell us about how they are classified?
Genus=Felis
Species=Felis catus
