B6- Inheritance, Variation And Evolution Flashcards
Where is the DNA found?
In the nucleus in animal and plant cells
What are chromosomes?
The structures that contain DNA
Describe the overall structure of a DNA molecule?
DNA is made of 2 strands of DNA coiled together. It has a double helix structure
DNA contains lots of sections called genes. Describe the function of genes
Genes code for particular sequences of amino acids which are put together to make specific proteins
What is meant by the term genome?
All genetic material in an organism
Give one reason why it is important for scientists to understand the human genome
It allows scientists to find genes that are linked to different types of diseases
What type of cell division is involved in the production of gametes?
Meiosis
Name a type of cell division used in asexual reproduction?
Mitosis
Cells produced by asexual reproduction are called clones. What does this mean?
They are genetically identical to the parent cell
Where in the body does meiosis take place?
In the reproductive organs
Before a cell starts to divide by meiosis, what happens to its DNA?
It is copied
How many cell divisions are there during the process of meiosis?
2 (before they spilt into four)
Briefly describe the results of meiosis
Meiosis results in four daughter cells being made that will have a complete set of chromosomes (half from mother and half from father) and every daughter cell will be genetically different
What type of cell division does the fertilised egg cell undergo?
Mitosis
The dividing cells form an embryo. What happens to the cells as it develops in order to form the whole organism?
Cells will differentiate into specialised cells
What is evolution?
Is the change in the inherited characteristics of a population over time
What does the theory of evolution say?
By natural selection, all organisms evolved from simple life forms that first started to develop over three billion years ago
What does it mean when a species becomes extinct?
No individuals of the species are alive
Give two factors which might cause a species to become extinct
New predators and new diseases
Describe how natural selection could have led to the evolution of hares with large ears, from a population of hares with smaller ears
What points would you include in this 6 marker?
- the original population would have had a variation of sizes of ears
- those with larger ears would lose more heat, meaning they are more likely to survive over hares with smaller ears
- the genes of larger ears would be passed on to offspring
- over time, population with larger ear gene will be more popular, leading to all hares having large ears
True or false
Antibiotics are drugs that kill all pathogens
False
True or false
Bacteria can evolve quickly because they divide very rapidly
True
True or false
Antibiotic-resistant bacteria don’t spread easily
False
How can farmers help to prevent the development of antibiotic-resistant bacteria?
By restricting the amount of antibiotics they give to their livestock
Give two reasons why the development of antibiotics is unlikely to keep up with the rate at which new antibiotic-resistant bacteria appear
It’s a slow process
It’s very expensive
Give one way in which doctors can help to prevent the overuse of antibiotics?
They only give it to patients that really need it
Explain why taking the full course of antibiotics reduce he chance of antibiotic-resistant strains developing
All bacteria will be killed, reducing the number of any individual bacteria becoming resistant to the antibiotic
What is selective breeding?
When humans choose which plants or animals are going to breed
What is another name for selective breeding?
Artificial selection
Suggest why dairy farmers might use selective breeding?
To get their cows to produce more milk
What is inbreeding?
When the best offspring breed
Inbreeding can make a population more likely to get a disease. Explain why
The animals are all closely related, they are less likely to have an allele that is resistant to that disease, meaning a lot or all of the animals will die quickly
Describe one other problem which may be caused by inbreeding
Genetic defects are more likely
What is genetic engineering?
The transfer of a gene from one organisms DNA into another organisms DNA
How can bacteria be genetically engineered to help someone with diabetes?
They cab be made to produce insulin
What is the benefit of genetically engineering crop plants to be resistant to herbicides?
It can increase crop yield
Give two ways in which crop plants are genetically engineered
To grow bigger and better fruit
To be resistant to insects
Suggest one thing the scientists could do to make their results more valid?
They could repeat their experiment with other meadows
True or false
Fossils are all between 100 and 1000 years old
False
True or false
Fossils are the remains of organisms
True
True or false
Fossils are often found in rocks
True
Why did many early forms of life not form fossils?
Because they were soft-bodied. They didn’t have skeletons
A fossilised insect is preserved in amber
The insect has been protected from moisture and oxygen. Explain why his has stopped the insect from decaying
Decay microbes need moisture and oxygen to survive. Therefore, as these factors are not present, the insect will not decay
Traces of organisms can also be considered fossils. Give two examples of a trace which may be left behind by an organism
Footprints
Rootlet traces
Apart from preserved organisms or traces left behind by organisms, give one other way in which fossils may be formed
When parts of the organism are replaced by minerals when they decay
What is the order of the 5 kingdom classification system?
Kingdom, phylum, class, order, family, genus, species
Which of the Linnaean system is the largest group?
Kingdom
What does the Linnaean classification system use to classify organisms?
Physical characteristics
What was the name of the scientist who proposed the three-domain system?
Carl woese
What are the three domains that Carl woese made up?
Bacteria
Eukaryota
Archaea
What is eukaryota?
This domain includes a wide range of organisms e.g. plants, animals, fungi and protists
What are archaea?
They live in extreme places such as hot springs and salt lakes
The scientific name of a hummingbird is a lophornis helenae. What is the genus of the hummingbird?
Lophornis
Which part of this word is the species and genus
Homo sapiens
Homo is the species
Sapiens is the genus
First word is the species, the second is the genus
Improvements in our understanding of organisms of to the development of new classification systems, like the three domain system. Give two of these improvements
Our understanding of the infernal structures of organisms has improved
Our understanding of the processes taking place inside organisms have improved
Give two types of data that can be used to make evolutionary trees
Current classification data and fossil records
Give one argument against embryo screening
It’s unfair treatment towards those that have a disease
Give one argument for embryo screening
It stops people from suffering
Which allele causes polydactyl?
A dominant allele (DD)
What allele causes cystic fibrosis?
Recessive (dd)
What does a carrier of cystic fibrosis genotype look like?
(Dd)
What is a mutation?
A random change in an organisms DNA that can be inherited
Helen and Stephanie are identical twins. Helen weighs 7KG more than Stephanie. Explain whether this is due to genes, environmental factors or both.
It must be environmental as the twins share the exact same genes
