B3.2 Flashcards
What is plasma?
The liquid part of the cell which carries a number of important substances around the body
What important substances do plasma carry around the body?
- Dissolved food substances, e.g. glucose
- Hormones from their glands to target cells
- Plasma proteins, e.g. antibodies
- Waste substances, e.g. urea
How are red blood cells adapted to their function (transporting oxygen)?
- Small so they pass through small blood vessels
- Shaped like biconcave disks for large surface area to exchange oxygen quicker
- No nucleus so more haemoglobin can fit in
How is oxygen transported in the body?
Haemoglobin in the red blood cells react with oxygen in the lungs forming oxyhaemoglobin. This process is irreversible. When the oxyhaemoglobin reaches the tissue, the oxygen is released
Name the three types of blood vessels.
- Arteries
- Veins
- Capillaries
What is the role of the arteries?
It transports blood away from the heart to the tissues
What is the role of the veins?
It transports blood back to the heart from the tissues
What is the role of the capillaries?
It links arteries to veins and allows material to pass between the blood and the tissues
What structure does the arteries have which made it adapt to its special role?
It has a thick muscular wall to resist the high pressure
What structure does the veins have which made it adapt to its special role?
Large valves and lumen to try and keep the blood moving back to the heart because the pressure is low
What structure does the capillaries have which made it adapt to its special role?
It has permeable walls so substances can be transferred between the blood and the tissues
How many chambers does the heart have?
4.
2 at the top and 2 at the bottom
Which chambers are larger (the top or the bottom)?
The bottom
What are the bottom chambers called?
The left ventricle and The right ventricle
What are the top chambers called?
The left atria and the right atria
What is the role of the atria?
They receive blood from veins and then they contract and force blood through valves into the ventricles.
What does the ventricle do when it receives blood from the atria?
It contracts and force blood out of the semilunar valve into the pulmonary artery
What is the valve on the right side called?
The tricuspid valve and it has 3 lobes
What is the valve on the left side called?
The bicuspid valve and it has 2 lobes
What do the biscupid, tricuspid and semilunar valve all do?
Prevent any backflow of blood
Whats so special about the pulmonary artery and the aorta?
Only arteries in the body with valves. (They both have semi lunar valves)
What does the pulmonary artery do when it receives the deoxygenated blood?
It takes the deoxygenated blood to the lungs
What happens when the deoxygenated blood is taken to the lungs?
It discharges the carbon dioxide carried and absorbs oxygen
What happens when the blood leaves the lungs?
The blood now oxygenated leaves the pulmonary vein at low pressure into the left atrium which contracts to force the blood out of the bicuspid valve
What happens when blood is forced out of the bicuspid valve?
The blood is now leaving at a high pressure through the left ventricle and through the aorta which pumps the blood to the rest of the organs around the body
Why does the left ventricle have a thicker muscle wall than the right ventricle?
Because it has to pump blood all around the body instead of the lungs which are just close by
Why is the heart called a double circulatory system?
Because the blood is pumped to the lungs and is returned to the heart to be pumped into the body. This means that the blood is at a higher pressure and flows at the tissue at a higher rate
How do bacterial cells differ from plant/animal cells?
- They don’t ave any mitochondria or chloroplasts
2. They don’t have a “true” nucleus just a small string of DNA floating freely in the cytoplasm
Why are stem cells called undifferentiated?
They can develop into different types of cells
What can stem cells be used for?
To treat some medical conditions
Where can stem cells be obtained from?
embyros
Why would people be for stem cell research in animals?
People think it’s acceptable because it can treat life-threatening diseases
Why would people be against stem cell research in animals?
People think it’s wrong because embryos are being destroyed
Where can stem cells also be obtained from?
Adults
Why do scientists prefer embryonic stem cells instead of animal cells?
Embryonic stem cells form a greater range of cell types and are easier to find
What are the differences between plant and animal growth?
- Animals only grow to a certain size but many plants carry on growing
- Plant cell division only happens in areas called meristems, found at the tips of roots and shoots
- The main way plants gain height is by their cells enlarging not dividing
- Many plants keep the ability to differentiate, but most animal cells lose it at a younger stage
How is growth measured?
In a growth curve
What is the best measure of growth?
Dry mass
What is another measure of growth?
Wet mass and height
What is the hardest way to measure for growth?
Wet mass because for some organisms, e.g. trees, but it’s easy with animals.
What is dry mass?
The dry matter of a sample or of an object when completely dried
How can dry mass be measured?
Killing the organism and all of the water content is removed, but it measures the true growth of the whole organism
How comes different parts of a whole organism may grow at different rates compared to the whole organism?
Because different parts of the organism may be needed at different types during the life of the organism
What can selective breeding programmes lead to?
Inbreeding = where two closely related individuals mate and this can cause health problem in species
What does inbreeding cause?
Inbreeding reduces the variety of alleles in the population. ( “the gene pool”)
What does the “gene pool” lead to?
- Increased risk of harmful recessive characteristics showing up in offspring
- A reduction in variation so that population cannot adapt to environmental changes
Name an advantage of genetic engineering
Organisms with desired features can be produced very quickly
Name a risk of genetic engineering
The inserted genes may have harmful side effects
Give examples of organisms that have been made with genetic engineering
- Genetically engineered bacteria that has been made to produce insulin
- Crops that have been made to be resistant to herbicides
Give reasons against genetic engineering
- Possible long term effects
2. Morally wrong, whatever the benefit
What are the 4 steps that are taken for genetic engineering?
- The desired characteristics are selected
- The genes responsible are identified and removed
- The genes are inserted into other organisms
- The organisms are allowed to reproduce
What is gene therapy?
The process of using genetic engineering to change a persons genes and cure certain disorders
What could gene therapy involve?
Gametes and body cells
Why would changing the genes in gametes be much more controversial?
It is difficult to decide which genes parents should be allowed to change. It could lead to “designer babies”
What is nuclear transfer?
Removing the nucleus from a body cell and placing it into an egg cell that has had its nucleus removed
Why would scientists clone animals?
- Mass-produce animals with desirable characteristics
- Produce animals that have been genetically engineered to provide human products
- Produce human embryos to supply stem cells for therapy
Name one ethical dilemma concerning human cloning
They will not be “true individuals”
How was Dolly the sheep made?
A technique called adult cell cloning
How does adult cell cloning work on Dolly?
- The donor had it’s nucleus removed
- The egg cell was replaced with the nucleus from an udder cell
- The egg cell was given an electric shock to make it divide like mitosis
- The embryo was implanted into a surrogate mother sheep
- The embryo then grew into a clone of the sheep from which the udder cell came
How could cloning technology be useful?
Genetically modified animals could be cloned to supply replacement organs for humans
Why are people worried about cloning technology being harmful towards humans?
These “replacement organs” could lead diseases being spread from animals to humans
What’s a disadvantage of cloning animals?
The success rate is 0.1 - 3%. This is bad because it’s a lot of effort for little success
What’s one more disadvantage of cloning animals?
Clones have a decreased life span
How can cloning in plants occur?
Naturally or help from humans
How do plants clone naturally?
Asexual reproduction
What are the advantages of cloning plants?
- Growers can be sure of the characteristics of each plant since all the plants will be genetically identical.
- It is also possible to mass-produce plants that may be difficult to grow from seed
What are the disadvantages of cloning plants?
- There is a lack of genetic variation
2. If the plants become susceptible to disease, then all the plants will be affected
Name a process of plant cloning
Tissue culture
Name the four steps of tissue culture
- A plant is selected that has certain characteristics
- A large number of small pieces of tissue are then cut from the plant
- The small pieces of tissue are then cut from the plant
- Aseptic technique is used to at all stages to stop any microbes infecting the plants
Why is cloning plants easier than cloning animals?
Many plant cells retain the ability to differentiate
