B13 - reproduction fact test

Question 1

what does sexual reproduction involve

Answer 1

the fusion of male and female gametes

Question 2

what is the female gamete in animals

Answer 2

egg cell

Question 3

what is the male gamete in animals

Answer 3

sperm cell

Question 4

what is the female gamete in flowering plants

Answer 4

egg cell

Question 5

what is the male gamete in flowering plants

Answer 5

pollen

Question 6

what does the formation of gametes involve

Answer 6

cell division called meiosis

Question 7

why are offspring produced through sexual reproduction genetically different

Answer 7

there is a mixing of genetic information

Question 8

what are the advantages of sexual reproduction

Answer 8

• produces variation in the offspring
• if the environment changes, variation gives a survival advantage by natural selection
• natural selection can be sped up by humans in selective breeding to increase food production

Question 9

what does asexual reproduction involve

Answer 9

only one parent and no fusion of gametes

Question 10

why are offspring produced through asexual reproduction genetically identical

Answer 10

there is no mixing of genetic information so this lead to clones

Question 11

how does asexual reproduction happen

Answer 11

mitosis

Question 12

what are the advantages of asexual reproduction

Answer 12

• only one parent needed
• more time and energy efficient as do not need to find a mate
• faster than sexual reproduction
• many identical offspring can be produced when conditions are favourable

Question 13

what is meiosis and what happens during it

Answer 13

produces gametes that have half the normal chromosome number and so when fertilisation happens the zygote has the full number of chromosomes again

1. normal cell, 46 chromosomes
2. DNA replicates
3. first cell division, 46 chromosomes
4. second cell division, number of chromosomes is halved so 23 chromosomes

Question 14

what are the similarities between mitosis and meiosis

Answer 14

• DNA replicates
• there is an increase in the number of sub-cellular structures

Question 15

what are the differences between mitosis and meiosis

Answer 15

• mitosis produces 2 daughter cells but meiosis produces 4
• mitosis has 1 cell division but meiosis has 2
• mitosis produces cells with 2 of each chromosome but meiosis produces cells with one
• mitosis produces genetically identical cells but meiosis produces genetically different cells

Question 16

what is a diploid cell

Answer 16

contains the full number of chromosomes e.g in humans 23 pairs

Question 17

what is a haploid cell

Answer 17

contains half the number of chromosomes e.g in humans 23 chromosomes

Question 18

what is DNA

Answer 18

a double stranded polymer wound to form a double helix. carries the genetic code

a polymer made from 4 different types of nucleotides

Question 19

what is a chromosome

Answer 19

a long coiled molecule of DNA that carries genetic information in the form of genes

Question 20

what is a gene

Answer 20

a section of DNA that codes for a specific sequence of amino acids that form a protein

Question 21

what is a genome

Answer 21

the complete genetic material of an organism

Question 22

what is the importance of studying the human genome

Answer 22

• search for genes linked to different types of disease
• understanding and treatment of inherited disorders
• use in tracing human migration patterns from the past

Question 23

what is an allele

Answer 23

a version of a gene

Question 24

what is a dominant allele

Answer 24

an allele that is always expressed, represented by a capital letter

Question 25

what is a recessive allele

Answer 25

an allele that i only expressed in the absence of a dominant allele, represented by a lower case letter

Question 26

what does homozygous mean

Answer 26

when someone has identical alleles of a gene e.g. ff

Question 27

what does heterozygous mean

Answer 27

when someone has 2 different alleles of a gene e.g Ff

Question 28

what is a genotype

Answer 28

an organism's genetic composition, describes all alleles

Question 29

what is a phenotype

Answer 29

an organism's observable characteristics, due to interactions of the genotype and the environment

Question 30

what does a nucleotide consist of

Answer 30

a common sugar and phosphate group with one of 4 different bases (A,T,C and G)

Question 31

which of the 4 bases bind to each other

Answer 31

A and T always bind C and G always bind

Question 32

what is DNA polymer made up of

Answer 32

repeating nucleotide units the long stands of DNA consist of alternating sugar and phosphate sections e.g strand of DNA: TGC CCG complimentary strand: ACG GGC

Question 33

what are proteins made from

Answer 33

chains of amino acids and are synthesised in ribosomes

Question 34

what is the code for a particular amino acid

Answer 34

a sequence of 3 bases

Question 35

what does the order of bases control

Answer 35

the order in which amino acids are assembled to produce a particular protein

Question 36

what is the process of protein synthesis

Answer 36

1. DNA can't leave the nucleus so a template is made (T is replaced with U) which leaves the nucleus and travels to the ribosome 2. proteins are synthesised on ribosomes, according to the template 3. carrier molecules bring specific amino acids to add to the growing protein chain in the correct order 4. when the protein chain is complete, it folds up to form a unique shape 5. this unique shape enables the proteins to do their job as enzymes, hormones or forming structures in the body such as collagen

Question 37

what is a mutation

Answer 37

a change in the DNA base sequence

Question 38

what do you need to know about mutations

Answer 38

- they are random and occur continuously - most don't alter the protein or only alter it slightly so that its appearance or function is not changed - a few mutations code for an altered protein with a different shape, an enzyme may no longer fit the substrate binding site or a structural protein may lose its strength - not all parts of DNA code for proteins, non-coding parts of DNA can switch genes on and off so variations in these areas of DNA may effect how genes are expressed

Question 39

what can a mutated gene lead to

Answer 39

an abnormal protein or no protein

Question 40

what does it mean if something is inherited in genetics

Answer 40

it is passed on from your parents

Question 41

what is hereditary a descriptive term for

Answer 41

conditions capable of being transmitted from parent to offspring through the genes

Question 42

what is polydactyly

Answer 42

a dominant condition where someone is born with extra fingers or toes

Question 43

what is cystic fibrosis

Answer 43

- an inherited recessive condition in which the lungs and digestive system can become clogged with thick, sticky mucus. - can cause problems with breathing and digestion from a young age. - over many years, the lungs become increasingly damaged and may eventually stop working properly

Question 44

when is an individual classed as a carrier of disease

Answer 44

when they have an allele for the disease in their genotype but it's not expressed in their phenotype (only for recessive diseases)

Question 45

what are reasons for embryonic screening

Answer 45

- reduces number of people suffering (ethical) - treating genetic disorders is expensive (economic) - many regulations in place so it doesn't get out of hand (social)

Question 46

what are reasons against embryonic screening

Answer 46

- could encourage people to pick characteristics creating designer babies (ethical) - expensive to carry out screening (economics) - may promote prejudice as it suggests those with genetic disorder are unwanted (social) - decisions about terminating pregnancy have to be made (social) - procedure can lead to miscarriage (social)

Question 47

what is gene therapy

Answer 47

the process by which normal alleles are inserted into the chromosomes of an individual who carries defective alleles e.g. those that cause a genetic disorder

Question 48

what are concerns associated with gene therapy

Answer 48

developing technology and not always successful same concerns as embryonic screening. many people believe gene alteration is unnatural, others think it helps alleviate suffering in those with genetic disorders