B6 Inheritance, Variation and Evolution

Question 1

what is mitosis

Answer 1

formation of two genetically identical cells from 1 cell

Question 2

what is meiosis

Answer 2

formation of 4 genetically non-identical cells (gametes) from 1 cell. These cells have half the genetic material of a normal cell.

Question 3

how many chromosomes are in 1 cell

Answer 3

46 (23 pairs of chromosomes)

Question 4

describe the stages of meiosis

Answer 4

-cell copies it’s genetic information so there is double the normal amount
-cells divide into two cells each with a full set of 23 pairs of chromosomes
-This cells then divide again into four cells each with 23 chromosomes, these cells are all genetically distinct

Question 5

what is a gene?

what information does a gene carry?

Answer 5

a small section of DNA on a chromosome

triplets of bases code for a specific amino acids which together can form proteins via protein synthesis.

Question 6

what is a genome

Answer 6

all of the genes for an organism

Question 7

what are nucleotides made of and where are they found

Answer 7

they comprise the DNA and are made of a sugar molecule, a phosphate molecule and an organic base (of which there are four different types).

Question 8

what are the four bases and which ones match with which

Answer 8

A with T and G with C

Question 9

describe the stages of protein synthesis

Answer 9

-the DNA unzips and is copied by mRNA: the sequence of bases for making the protein (this is because the DNA cannot leave the nucleus).
-the mRNA then passes through the ribosomes (which are in the cytoplasm)
-The corresponding amino acids are brought to the ribosome and joined and folded to form a protein (proteins have a unique 3D structure).

Question 10

what is a phenotype

Answer 10

All of the physical characteristics of an organism

Question 11

what does being polydactyl mean

Answer 11

having extra fingers or toes as a result of a dominant allele

Question 12

what is cystic fibrosis

Answer 12

a disorder that produces thick mucus in the airways or pancreas caused by a recessive allele

Question 13

what are the alleles of a man and woman

Answer 13

man= XY woman= XX

Question 14

what is evolution

Answer 14

the change in shared characteristics over time

Question 15

explain the theory of evolution

Answer 15

-variation between organisms created through mutation and sexual reproduction
-if the mutation gives a survival advantage the organism is more likely to survive and pass on those genes to it’s offspring
-Over many generations, the frequency of the mutation increases in the population: evolution

Question 16

what is selective breeding

Answer 16

where people will choose which organisms to breed in order to create valuable traits

Question 17

What are two advantages of sexual reproduction?

Answer 17

Produces variation in offspring –> allows natural selection and evolution to occur.

Allows humans to selectively breed animals to produce offspring with the best combination of characteristics.

Question 18

What are three advantages to asexual reproduction?

Answer 18

Only one organism required.
–>Less energy required and faster.
–>Lots of offspring can be produced quickly in favourable conditions.

Question 19

What is the importance of non-coding sections of DNA (do not code for proteins)?

Answer 19

Determines which genes are expressed

Question 20

What is genotype?

Answer 20

The combination of alleles that an individual has

Question 21

name the 8 things living things are divided into

Answer 21

domain, kingdom, phylum, class, order, family genus, species

Question 22

what are the three domains

Answer 22

bacteria, Archaea, eukaryotes

Question 23

explain how genetic engineering works

Answer 23

-genes from chromosomes are cut out using restriction enzymes leaving a sticky end
-a virus or bacterial plasmid is cut with the same enzyme
-they are joined together by DNA ligase enzymes
-the combined loop is placed in a vector and allowed to multiply as it will now contain the modified gene

Question 24

what are some advantages and disadvantages of GM crops

Answer 24

Adv:
-improve growth rate
-can make crops grow in hotter or colder regions
-plants can make their own pesticide or herbicide
-greater yields can help solve world hunger

Dis Adv:
-may effect wild flowers and insects
-we don’t know how GM crops effect humans
-could create super weeds and pests

Question 25

explain embryo transplants

Answer 25

-in a lab sperm and egg cells with desired characteristics are fused in a lab to create an embryo
-the embryo divides many times and is inserted into the mother

Question 26

explain adult cell cloning

Answer 26

-nucleus is removed from an unfertilised egg
-nucleus from an adult body cell is removed and placed in the denucleated egg cell
-placed into the female and is birthed a clone of the adult cell