Biology - Additional 2 Flashcards
What is respiration?
Is the process of releasing energy from glucose which goes in every cell
What is the equation of the aerobic respiration?
Glucose + oxygen > carbon dioxide + water
What does aerobic respiration do?
Builds larger molecules from smaller ones
Allows muscles to contract
In mammals and birds its used to keep their body temperature steady
In plants its used to build sugar and nitrates and others into amino acids and then proteins
What happens when you exercise?
- increases the breathing rate and makes you breath more deeply for oxygen
- increase in muscle activity so more oxygen and glucose is required also more carbon dioxide needs to be removed this happens so blood needs to flow faster
- heart beats harder
What is glycogen used for?
During exercise the muscles use glucose rapidly and need to convey glycogen back into glucose
What is wrong with anaerobic respiration?
Cannot supply enough oxygen to muscles
Respiring without oxygen this is incomplete breakdown of glucose which produces latic acid
- produces less energy
- painful and causes muscle fatigue so the muscles get tired and contact inefficiently
But they keep muscles for a little while longer
What is the equation of anaerobic respiration?
Glucose> energy + latic acid
What is oxygen debt?
Its used to repay oxygen
Keep breathing hard after you stop to get more oxygen so latic acid can be oxidised to form carbon dioxide and water
How do fossils form in rocks?
- Gradual replacement by minerals, bones don’t decay and last a long time while buried, eventually replaced by minerals as they decay they form a rock like substances shaped like the original hard part, surrounding sediments also turn rocks but fossils stay distinct inside the rock
- Casts and impressions, fossils are formed when the organism is buried in soft clay, the clay hardens around the organism as it decays leaving a cast of itself
- Preservation, places where no decay happens so there is no oxygen, moisture or in glaciers where it is too cold or in peat bogs where it is to acidic
Why don’t people know how life began?
- lack of valid and reliable
- soft bodied and soft tissue decayed completely so the fossil record is incomplete
- fossils that formed millions of years ago have been destroyed by geological rocks
Why does the extinction happen?
- cant evolve quickly enough
- environment changes
- new predator kills them all
- new disease kills them all
- cant compete with a new species for food
- catastrophic event that kills them all
- a new species develops
What is speciation?
The formation of a new species
What is an endemic organism?
When a species evolves in isolation and is only found in a place in the world
Describe the process of speciation
- A group of organisms become separated and isolated through geographical isolation
- Conditions in the other environment are different so different characteristics will become more common due to natural selection
- There is variation in the group and a allele is selected that makes them better adapted
- Better chance of survival and passing on their gene to the offspring
- This happens until they can no longer interbreed with the original group so they have become a separate species
What is mitosis?
Asexual cell division where two identical cells are formed
What is the purpose of mitosis?
To make new cells for growth and repair
Describe the process of mitosis?
- Cell gets signal to divide
- Cell duplicates its DNA
- The chromosomes line up in the centre of the cell
- Cell fibres pull the arms of the DNA apart
- The two arms of each chromosome go to opposite parts of the cell
- Membranes form around the two sets of chromosomes
- Cytoplasm divides and 2 new cells are produced
How does asexual reproduction happen?
Via mitosis
The offspring has the exact same genes as the parent so there is no variation
What is meiosis?
Its the two stage process of cell division which reduces the chromosome number in the daughter cells, its involved in making gametes for sexual reproduction
Describe the process of meiosis
- Cell duplicates its DNA
- In the first division the chromosome pairs line up in the centre of the cell
- The pairs are pulled apart so each new cell has one copy of each chromosome
- In the second division the chromosomes line up in the centre of the cell
- Cell fibres pull arm of the chromosome apart
- Four gametes with only one set of chromosomes in it are produced
What does DNA contain?
Instructions to put an organism together and make it work
Where is DNA found?
In the nucleus, in long molecules called chromosomes
What is a gene?
A section of DNA
What does a gene contain and do?
A gene contains instructions to make a specific protein
The cell then makes proteins by putting together amino acids in a particular order, the genes tell the cell what order to put the amino acids in
What is DNA useful for?
Forensic science
Paternity testing
How do tell people apart by using DNA
Cut persons DNA into small sections and then separate them, everyone has a unique pattern so you can tell people apart
What is the proposal for a national genetic database?
Its a system that can compare DNA at a crime scene or in general to everyone in the country
What are the advantages and disadvantages of a national genetic database?
- invasion of privacy
- how safe it is
- misinterpreted data
- scientific problems
What are stem cells?
Cells that can turn into any type of cell because they are undifferentiated
Where are stem cells found?
Bone marrow, adult stem cells cannot turn into any cells but only certain ones unlike embryonic stem cells that can turn into any cell
What can stems cells be used for?
To cure disease
- blood disease, bone marrow transplant
- faulty cells
How do you control the differentiation of stem cells?
By controlling the environment they are growing in, you do this in order to get one specific cell
What are advantages and disadvantages of embryonic cell research?
- shouldn’t be used in experiments as each one is a potential life
- scientists should concentrate on developing other sources of stem cells without the need of embryos
+ curing patients who already exist and who are suffering are more important than the rights of an embryo
+ usually unwanted embryos that would be destroyed anyway
What chromosomes do men have?
X and Y
What chromosomes do women have?
XX
Why will there always be an X chromosome?
Because the egg is always X
Who was Gregor Mendal?
An Austrian monk who discovered “hereditary units” - genes
What did Mendal purpose?
- characteristics were determined by hereditary units
- hereditary units are passed on from both parents, one unit from each parent
- hereditary units can be dominant of recessive
What is an allele?
A different version of the same gene
What does homozygous mean?
Two alleles for a particular gene are the same
What is heterozygous?
Two alleles for a particular gene are different
What is phenotype?
the characteristics that you display
What is genotype?
The combination of alleles you have in a gene
What is cystic fibrosis?
A genetic disorder, thick sticky mucus is produces in the air passages and the pancreas
- caused by a recessive allele
- for the offspring to get it, both parents must be carriers or sufferers
What is polydactyl?
When a child has extra fingers or toes
- caused by a dominant allele
- only one parent needs to have it for it to be inherited
What is embryonic screening?
Before an embryo is implanted they remove it and analyse its genes, this is the way genetic disorders are checked
What are the advantages and disadvantages of embryonic screening?
- everyone wants to screen an embryo so they can pick the most desired one
- rejected embryos are destroyed, these could have developed into humans
- prejudice, people with genetic problems are undesirable
- expensive
+ stops people from suffering
+ laws stop it from going to far
+ during IVF most embryos are destroyed anyway
+ treating disorders cost a lot of money
