B6- Inheritance, Variation And Evolution
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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