How do plants and animals grow differently?
- animals grow until they reach a finite size (full growth) and then stop growing
- plants often grow continuously
- animal growth happens by cell division
- plant growth in height is mainly due to cell elongation. Growth by division usually only happens in areas of a plant called meristems (at the tips of the roots and the shoots
What is differentiation?
- the process by which a cell changes to become specialised to its jobs
- in most animal cells this ability is lost at an early stage, most plant cells don’t lose this ability
What are stem cells?
- some cells are undifferentiated
- they can develop into different types of cells, tissues and organs depending on the instructions given
- found in early human embryos, they have the potential to turn into any kind of cell at all
- adults have stem cells in certain places, like bone marrow, but they are not as versatile as embryonic stem cells, they can only turn into certain cell types
How may stem cells be able to cure disorders?
- people with blood disorders can be cured with bone marrow transplants (bone marrow contains adult stem cells that turn into only new blood cells)
- scientists can extract and grow very early human embryonic stem cells
- they may eventually be able to grow tissues to treat medical condition, e.g. nerve cells to cure brain damage and spinal injury, skin cells for skin grafts
- this is stem cell therapy
Why are people against stem cell research?
- they feel human embryos shouldn’t be used for experiments since they are potential human life
- some countries won’t fund research to make new stem cell stocks for scientists, but in the UK it’s allowed as long as strict guidelines are followed
What are the different ways to measure growth?
- length
- dry mass
- wet mass
What is the best measurement of growth?
-dry mass because it is not effected by changes in water content and tell you the size of the whole organism
What are the disadvantages and advantages of measuring growth with length?
- advantages:easy to measure
- disadvantages:does not tell you the width, diameter, number of branches, etc
What are the disadvantages and advantages of measuring growth with wet mass?
- advantages:easy to measure
- disadvantages:very changeable, e.g. a plant will be heavier after recent rainfall as it absorbed lots of water and animals will be heavier after eating or having a full bladder
What are the disadvantages and advantages of measuring growth with dry mass?
- advantages:not affected by amount of water in a plant or animal, or how much an organisms has eaten
- disadvantages:you have to kill the organism to work it out
What are the main phases of human growth?
- infancy: roughly the first two years of life. Rapid growth
- childhood:period between infancy and puberty. Steady growth
- adolescence:begins with puberty and continues until completion of body development and growth. Rapid growth
- maturity/adulthood:period between adolescence and old age. Growth stops
- old age: usually considered to be between 65 and death
What is the word equation for aerobic respiration?
glucose+oxygen–>carbon dioxide+water (+energy)
What is the word equation for anaerobic respiration?
glucose–>lactic acid (+energy)
What is ATP?
- a substance made by respiration
- acts as the energy source for many cell processes and transports energy to where it is needed in a cell
What is respiration?
- occurs in every cell
- the process of releasing energy from glucose
- the energy from respiration cannot be used directly, so it’s used to make a substance called ATP
- controlled by enzymes, meaning rate of respiration is affected by temperature and pH
What is aerobic respiration?
- respiration when plenty of oxygen is available
- the most efficient way to release energy from glucose
- when rate of respiration increases, oxygen consumption and carbon dioxide production increase
- therefore the rate of oxygen consumption can be used to estimate metabolic rate (the amount of energy being used)
What is anaerobic respiration?
- releases much less energy per glucose molecule
- during vigorous exercise the body can’t supply enough oxygen to muscles for aerobic respiration–despite your heart rate and breathing rate increasing as much as they can. So muscles have to start respiring anaerobically.
- glucose is only partially broken down
- lactic acid is produced and builds up in the muscles, which gets painful and make muscles fatigued
What happens after you finish doing really vigorous exercise
- you have an oxygen debt. You need extra oxygen to break down all the lactic acid that’s built up in your muscles and to allow aerobic respiration to begin again
- meaning you breath hard a while after you stop exercising to repay the debt
- lactic acid is carried to the liver to be broke down, so your heart rate has to stay high too
- an advantage is you can still use your muscles
What is respiratory quotient?
-RQ tells you whether someone is respiring aerobically or anaerobically
Why are people for stem cell research?
- curing patients who already exist and are suffering is more important than the rights of embryos
- the embryos used in the research are usually unwanted ones from fertility clinics. If they weren’t used for research they they would probably be destroyed
What is the formula for respiratory quotient?
RQ=amount of CO2 produced/amount of 02 used
What respiratory quotients show aerobic and anaerobic respiration?
- 0.7-1:aerobic
- greater than 1: anaerobic
