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SB3
Pearson GCSE Separate Science Biology
| Question | Answer |
|---|---|
| What is the name of the gap between two neurones? | Synapse |
| What is the definition of a reflex arc? | A neurone pathway that doesn’t use the parts of the brain involved in processing information. This results in a quicker response. It protects a person from injury |
| Name the main parts of the reflex arc in the correct order | Stimuli, Receptor cells, sensory neurone, relay neurone, motor neurone, effector |
| Define the term effector? | Part of the reflex which carries out a response/action |
| Name two examples of effectors and state what each do when they receive an electrical impulse | Muscle (contracts) or gland (secretes / releases a substance) |
| Name the chemical that crosses a synapse | Neurotransmitter |
| Name the “message” that travels along a neurone | Electrical impulse |
| Define asexual reproduction | The reproduction of an organism without fertilisation |
| Which type of reproduction requires only 1 parent organism? | Asexual Reproduction |
| Explain is sexual reproduction advantageous? | Organisms produced are genetically different and better suited to an environment than others, this means they will survive and reproduce. |
| What is the control centre of a cell called? | (nucleus) |
| What structures are found inside the nucleus? | (chromosomes) |
| What substance forms a long strand in each chromosome? | (DNA) |
| How do body cells make copies of themselves? | (cell division, mitosis) |
| How many chromosomes are there in a human body cell nucleus? | -46 |
| What happens in fertilisation? | (two gametes fuse) |
| What is the name of the cell formed in fertilisation? | (zygote, fertilised egg cell) |
| What would happen to the number of chromosomes in a zygote if two body cells were used in fertilisation? | (it would have twice the number it should) |
| How many chromosomes does a human gamete contain? | -23 |
| The DNA strand in a chromosome contains sections that contain instructions for characteristics. What are these sections called? | (genes) |
| What molecule forms the genome of an organism? | (DNA) |
| Where are genes found? | ([in sections of DNA] on chromosomes) |
| What does a gene carry the instructions for? | (making a protein) |
| A protein is made by linking together smaller molecules. What are these smaller molecules called? | (amino acids) |
| What is any molecule made of repeating units called? | (a polymer) |
| A human cell contains 46 strands of DNA. Is it diploid or haploid? | (diploid) |
| Are the cells produced by meiosis haploid or diploid? | (haploid) |
| Are the cells produced by mitosis haploid or diploid? | (diploid) |
| What shape is DNA? | (a double helix) |
| What is a chromosome made out of? | (DNA and proteins [to package the DNA]) |
| What shape is a DNA molecule? | (double helix) |
| What part of a DNA strand contains the instructions for a protein? | (gene) |
| What are the letters of the bases that form the DNA code? | (A, C, T and G) |
| How do these bases pair up in DNA? | (A with T, C with G) |
| Apart from bases, what other parts are needed in a DNA molecule? | (phosphate group, sugar) |
| What is one phosphate group, one sugar and one base called? | (nucleotide) |
| Why is DNA a polymer? | (It is made of many nucleotides joined in a chain.) |
| Why are proteins polymers | (They are made of many amino acids joined in a chain.) |
| Give an example of a protein. | (any example, e.g. an enzyme) |
| How is the active site of an enzyme formed? | (by folding of protein/polypeptide/amino acid chains) |
| What molecule is produced in transcription? | (mRNA or messenger RNA) |
| What base does mRNA contain that DNA does not? | (uracil) |
| What is the name of the enzyme that allows transcription to occur? | (RNA polymerase) |
| The mRNA nucleotides fit together with the nucleotides on the DNA template strand. What word describes bases that fit together? | (complementary) |
| Where does transcription occur in a cell? | (nucleus) |
| Where does translation occur in a cell? | (cytoplasm) |
| What has to bind to an mRNA molecule for translation to occur? | (ribosome) |
| What does translation produce? | (a polypeptide) |
| What molecule carries amino acids to the mRNA in the ribosome? | (tRNA) |
| What has to happen to the polypeptide for an enzyme in order for it to become a functional enzyme? | (It has to fold.) |
| How many bases does a codon contain? | (three) |
| What does each codon contain the code for? | (the addition of a particular amino acid to the polypeptide chain) |
| What is the name of the process in which the genetic code is used to make a polypeptide? | (translation) |
| A change in the bases of a gene creates a genetic variant. What is this sort of change called? | (mutation) |
| Why might a mutation in a codon not cause a change in the polypeptide produced? | (It does not affect the amino acid that is coded for.) |
| Why can a difference of a single amino acid change how a protein functions? | (It can interfere with the way the polypeptide chain(s) fold(s).) |
| What has to bind to an mRNA molecule for translation to occur? | (ribosome) |
| Why might a mutation in the non-coding region before a gene cause an increase in the production of a certain protein? | (The mutation causes RNA polymerase to bind better.) |
| What is an organism’s phenotype? | (its observable characteristics) |
| What shape is a DNA molecule? | (double helix) |
| What part of a DNA strand contains the instructions for a protein? | (gene) |
| What are the letters of the bases that form the DNA code? | (A, C, T and G) |
| How do these bases pair up in DNA? | (A with T, C with G) |
| Apart from bases, what other parts are needed in a DNA molecule? | (phosphate group, sugar) |
| What is one phosphate group, one sugar and one base called? | (a nucleotide) |
| Why is DNA a polymer? | (It is made of many nucleotides joined in a chain.) |
| Why are proteins polymers? | (They are made of many amino acids joined in a chain.) |
| What is a zygote? | (a fertilised egg cell) |
| Why do people have naturally different colours of hair? | (They have slightly different genes.) |
| What are different versions of the same gene called? | (alleles) |
| What sort of variation do alleles cause in organisms? | (genetic variation) |
| When we consider one gene, what word is used to say that both alleles are the same? | (homozygous) |
| If a dominant allele has the letter A, how would you show that an organism is heterozygous? | (Aa) |
| What word describes the characteristics caused by the alleles of a gene? | (phenotype) |
| What word describes the alleles of a gene found in an organism? | (genotype) |
| What word describes an allele that only has an effect if an organism has two copies? | (recessive) |
| A genotype is written QQ. What does this tell you? | (It is homozygous for the dominant allele.) |
| What is a probability? | (the chance of an event occurring) |
| If the occurrence of an event has a probability of 1, what does this mean? | (It is certain to occur.) |
| What is monohybrid inheritance? | (inheritance of alleles of one gene) |
| How can we show the possible inheritance of alleles by offspring from their parents? | (genetic diagram, Punnett square) |
| Which type of diagram is used to show the inheritance of a characteristic through different generations in a family? | (family pedigree) |
| If the genotype for one gene of a rabbit is Bb, where B is the allele for brown coat and b the allele for black coat, what is the rabbit’s phenotype? | (brown) |
| What are the possible allele combinations of offspring from heterozygous parents who are both Aa for a gene? | (AA, Aa and aa) |
| A human egg cell that contains an X sex chromosome is fertilised by a sperm cell containing a Y sex chromosome. What will be the sex of the baby that develops? | (male) |
| What is the theoretical probability of a couple having a baby boy? | (probability 50 per cent or half) |
| In monohybrid inheritance, what is the theoretical probability of parents who are both heterozygous for a gene producing an offspring that is also heterozygous for the gene? | (probability 50 per cent or half) |
| In monohybrid inheritance, what is the theoretical ratio of dominant to recessive phenotypes produced by parents who are both heterozygous for the characteristic? | (3 : 1) |
| What letters are used to describe the different human blood groups? | (A, B, O) |
| Name the two types of cell division. | (mitosis and meiosis) |
| Which type of cell division produces sex cells? | (meiosis) |
| What happens to the chromosomes in a nucleus just before cell division starts? | (Chromosomes are copied/duplicated.) |
| Which subunits are proteins made of? | (amino acids) |
| Name the four bases in DNA. | (adenine, thymine, cytosine, guanine) |
| What is the name given to part of a DNA molecule that codes for a protein? | (gene) |
| Why do different pieces of DNA produce different proteins? | (because they have different sequences of bases/produce different sequences of amino acids) |
| Why can DNA be matched to the person it came from? | (Everybody has a slightly different order of bases intheir DNA.) |
| True or false: 50 per cent of a boy’s genes come from his mother. | (true) |
| If we all have the same genes, why do we look different? | (We have inherited different alleles.) |
| What is the phenotype of an organism? | (what it looks like/the obvious characteristics) |
| What is the genotype of an organism? | (the combination of alleles in its genes) |
| Is human eye colour coded for by one gene or many genes? | (many) |
| One gene codes for the cell membrane protein CFTR. There are many alleles for the CFTR gene. How many alleles do you have for the CFTR gene in one of your body cells? | (two) |
| A mutation of the CFTR gene can lead to the disorder cystic fibrosis. What is a mutation? | (a change in the order of bases that form the gene) |
| Cystic fibrosis is an inherited disorder. What does that mean? | (It is passed from parent to offspring in the genes in a gamete.) |
| What research, finished in 2003, was the first effort to map a complete human genome? | (Human Genome Project) |
| How could a map of a person’s genome help identify diseases they might develop? | (Some alleles show an increased risk for the person of developing a genetic disorder.) |
| How could a map of a person’s genome help identify which medicines they should be given? | (Some alleles affect how well medicines work in the body, including problems they can cause.) |
| Many mutations have no effect on the phenotype. Explain why. | (They do not change the protein that is coded for by the gene.) |
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Davenant Foundation School
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