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how are cells organised to form organisms (moral and social issues related…
how are cells organised to form organisms
do all cells do same job?
a school usually has principal, vice principal, teachers, admin officers and canteen vendors. each person does specific job to keep school running smoothly
similarly, multicellular organisms have cells that come in all shapes and sizes. in human body, eg, there are about 200 different types of celles. each type of cell does specific job to help body function.
cells that have specific jobs are called speciallised cells.
pg 143
from cells to tissues
when cells of same type do same job, we say that they make up a tissue. eg, every muscle tissue makes muscle contract to cause body movement.
pg 144 and 145
from organs to systems
when different organs work together to do particular job, they make up system. system consists of parts that work tgt
each system in human body has one main function
pg 146
plants also have systems
transport system is one important system in plant
organs that make up this system are roots, stems and leaves
this system carries water, food and other substances to various parts of plant
from systems to organs
in multicellular organism, different systens makke up whole of organism.
unicellular organisms dont have any tissues, organs or systems as they have only 1 cell
how do cells work together
have you noticed that it's more time consuming to work on school project . yourself that if you worked in small grp of friends?
if can divide project into smaller tasks for different people to handle, work can become more manageable
as unicellular organism has only 1 cell, this cell has to carry out all jobs of organism such as respiration, digestion and reproduction
however, in multicellular organism, different cells carry out different jobs
dividing work of organism among different cells is called division of labour
division in multicellular organisms have several advantages
organism can perform more tasks (than unicellular organisms)
increases efficiency. eg, red blood cell carry oxygen around body and do not have to be involved in other taskks
cells live longer
pg 148
besides division of labour among cells, there is also division of labour among organs and systems. different organs and systems do different jobs
in human body, heart and brain do different jobs. in spite of all this, all organs organs work with one another to makke up system and many systems work together to ensure that whole organism functions effectively
149-150
moral and social issues related to organ donation and genetic testing
organ donation
every day, people in SG die because body organs are diseased and are no longer working properly
lives of these people can be saved if they receive healthy organ from another person
doctors can replace diseased kidney with healthy kkidney from another person
called organ donation
organs that are donated include livers, kkidney, heart and lungs
usually, organ comes from person who has just dies
but kidney and parts of liver can also come from living person
first kidney transplant in SG was performed in 1970.
first heart and liver transplants tookk place in 1990
should people be required to become organ donors? in SG, all citizens must be organ donors unless they have explicitly opted out
should people be paid to donate organs? many healthy people in poor countries donate their organs in order to get money
people suggested that suitable animal organs can be used for humans. is this right?
some people think that we should not donate organs . eg, they think body must be intact when buried. however, others feel that we must encourage organ donation or many sick people will die
pg 151
genetic testing
nucleus in cell contains chromosomes and each chromosome is made up of genes
pg 152
pg 153-155