B2 Topic 1

Question	Answer
What is the function of the cell membrane	Controls movement of substances in and out of the cell
What is the function of the cell wall	supports the cell
What is the function of the chloroplast	photosynthesis takes place in this organelle
What is the function of the mitochondria	respiration occurs in this organelle
What is the function of the vacuole	It helps support the plant by keeping the cell rigid
which type of microscope has the largest magnification?	Electron microscope
State 2 differences between a bacterial cell and an animal cell	bacterial cell has plasmids, a flagellum and a cell wall unlike the animal cell. bacteria cell has a circular loop of DNA whereas the DNA in an animal cell are in chromosomes. animal cell has a nucleus and the bacterial cell does not
Define the term 'gene'	A section of DNA which codes for a specific protein
Describe the structure of a DNA molecule	Double helix - two strands held together by hydrogen bonds between complementary bases
State the complementary base pairs found in DNA	A = T, G = C
How is complementary base pairing different if DNA is pairing with mRNA?	A pairs with U instead of T. T is replaced by U in mRNA
What chemical substances would you need to extract DNA from kiwi?	Salt, water, washing up liquid (protease)
Which scientists cracked the DNA code?	Watson and crick
What was the purpose of the Human Genome Project?	To sequence all of the bases in the human genome
State 2 benefits of the human genome project	Improved genetic testing for disorders; New ways of finding genes that increases the risk of disease; New treatments and cures; Personalised medicines that work with a particular genotype; New was of looking at changes in genome over time
What is a plasmid?	A circular loop of DNA
Define genetic engineering	Altering the DNA of an organism by inserting DNA from another organism into its genome
What are used to cut the DNA and stick it into the genome of the new organism?	Enzymes
one advantage and disadvantage of genetic engineering for 'beta carotene in golden rice'	Advantage: it's used to make vitamin A which will reduce death and blindness Disadvantages: Can cross breed with wild rice contaminating its DNA. Can be expensive to buy because it produces sterile seeds so farmers have to buy them every year
one advantage and disadvantage of genetic engineering for 'producing insulin in bacteria'	Advantages: It can be used by vegans, Supply not affected by animal disease or demand for meat, it can be made in vast quantities it's cheaper Disadvantages: Bacteria produce insulin quite differently so it many not work on some people
one advantage and disadvantage of genetic engineering for 'the production of herbicide resistant crops'	Advantages: Reduces the amount of crop spraying Disadvantages: Herbicide resistant weeds can develop, Cross pollination with wild plants, Potential loss of biodiversity
Number of daughter cells formed in Mitosis and Meiosis	Mitosis - 2 Meiosis - 4
Are the daughter cells identical to the parent cell in Mitosis and Meiosis?	Mitosis - Yes Meiosis - No
Do the daughter cells in Mitosis and Meiosis have a haploid or diploid nuclei?	Mitosis - Diploid Meiosis - Haploid
What is Mitosis is used for?	Growth and repair
What is Meiosis used for?	Making gametes
Define Fertilisation	When haploid gametes join to form a diploid zygote
Define Cloning	The production of a genetically identical individual. An example of asexual reproduction
What are the 5 stages of cloning a mammal?	1. Remove a diploid nucleus from a body cell. 2. Enucleate an egg cell. 3. Insert diploid nucleus into enucleated egg cell. 4. Stimulate the diploid nucleus to divide by mitosis. 5. Implant into surrogate mother.
What is the main source of stem cells in research? What ethical issue is associated with this source?	Discarded embryos from fertility treatment. Embryo destroyed in the process.
one advantage and disadvantage of cloning	Advantages: Can make a genetically identical copy of an animal with desirable characteristics. Can be used to make copies of GM animals to guarantee all offspring have the trait Disadvantages: Cloned animals often die young Cloned animals often age quicker It is also a complicated process
one advantage and disadvantage of 'embryonic stem cell research'	Advantages: They can develop into almost every type of human cell. Bone marrow stem cells can be used to treat leukemia. Disadvantages: They can come from leftover embryos from fertility treatments. Risk of rejection. Could lead to tumours forming
What provides the code for the structure of protein?	The sequence of bases on the DNA
List the 5 stages of protein synthesis	1. Double helix unzips 2. The complementary mRNA strand is made in the nucleus and passes out through a pore 3. mRNA attaches to the ribosome 4. A triplet of bases on the mRNA (codon) code for a specific amino acid 5. tRNA transfers amino acids to the ribosome
What is a mutation?	A change in the sequence of bases in the DNA
What are the units that make up proteins?	Amino Acids
Proteins are specific. What does this mean?	They have a specific shape, they have a specific sequence of amino acids
What is an enzyme?	A biological catalyst
How does temperature affect enzyme activity?	It speeds up its activity up to 40 degrees Celsius after which it denatures and stops working
How does pH affects enzyme activity?	Enzymes only work at a specific pH. Either side of the optimum, it will not work as well.
Where in the enzymes does the reactions take place?	Active site
If an enzyme is denatured, what does it mean?	The shape of the active site has changed
Describe one use enzymes outside the body?	Digestion - many enzymes break larger molecules down into smaller ones in digestion. Stain digesting enzymes in washing powders break down stains in clothes. Microorganisms excrete enzymes onto food to break them down outside the body and then absorb the products
State 2 processes inside the body that use enzymes.	DNA replication and Protein synthesis

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