Revision for September Flashcards
How does each colony of bacteria grow?
through cell division
Why is it important to sterilise apparatus before use?
to prevent contamination in order to prevent other organisms from affecting the results
Why are Petri dishes incubated at 25 degrees celsius at school?
to prevent the growth of pathogens
Why would an investigation be repeated?
to improve the reliability of the investigation
to check for anomolies
Key features of asexual reproduction:
requires only one parent
parent produces genetically identical clones of itself
no mixing of genetic material
in this type of reproduction, body cells divide by mitosis
what are the male + female chromosomes?
female: 2X chromosomes
male: 1X 1Y chromosomes
Why use stem cells?
stem cells can differentiate
stem cells can divide
what are the uses of stem cells?
medical research, medical treatment
Why may people reject use of Stem cells from embryos?
it is unethical, religious reasons, could cause harm to embryos
Why do human skin cells need to divide?
for growth + repair
Human stem cells can treat…
paralysis
Process of mitosis:
DNA replicates to form 2 copies of each chromosome
the cell grows and copies its internal structures
one set of chromosomes is pulled to each end of the dividing cell + the nucleus divides
the cytoplasm + cell membrane divides to form 2 identical daughter cells
How do prokaryotic organisms undergo cell division?
binary fission
Why would cell division stop?
shortage of nutrients
so cells die
Why can an immature egg not be used to produce a baby?
egg only contains the genetic information of the mother
it’s asexual as there is no sperm involved
ethical/moral/religious issues
cells used to treat disease cannot later be used to produce a baby
Why do most organisms have an even number of chromosomes?
chromosomes come in pairs
organisms inherit one of each pair form each parent
What substances do plants absorb by active transport?
minerals
ions
Describe the function of muscle cells in the wall of the stomach.
to contract
to churn food
Function of mitochondira:
to transfer energy for use
by respiration
Describe how a student should prepare an uncontaminated culture of a bacterium in a Petri dish.
Sterilise the Petri dish and agar plate before use.
This kills any unwanted bacteria and prevents contamination.
Then pass the inoculating loop through a Bunsen burner flame to sterilise it.
Next, keep the lid of the Petri dish open as little as possible and spread the bacterium onto the agar plate using the inoculating loop.
This is to prevent microbes from the air entering and contaminating the agar plate.
Then seal the lid of the Petri dish using tape, which prevents it from falling off and allowing microbes to enter from the air.
Finally, incubate the agar plate to allow for the growth of bacteria.
What are the areas in which bacteria have not grown on an agar plate called?
zone of inhibition
How can a vaccine limit the number of people with a virus?
can provide immunity
can prevent virus from spreading