Science - Test #1

Question 1

what does dna stand for?

Answer 1

deoxyribonucleic acid

Question 2

what is dna’s job?

Answer 2

to control all activities in the cell

Question 3

what is the 3d shape of dna called?

Answer 3

double helix

Question 4

dna is made up of small building blocks which are called?

Answer 4

nucleotides

Question 5

what does each nucleotide have?

Answer 5

a phosphate, a deoxyribose sugar and a base

Question 6

what are the four base names?

Answer 6

adenine, thymine, cytosine, guanine

Question 7

what bases pair with eachother?

Answer 7

adenine and thymine

cytosine and guanine

Question 8

nucleotides join together to form two long chains. what does each chain have?

Answer 8

a sugar-phosphate backbone on the outside

Question 9

the sugar-phosphate backbone on the outside looks like a ladder. The ‘steps’ on the ladder are the bases and they are held together by what?

Answer 9

hydrogen bonds

Question 10

what is a gene?

Answer 10

a segment of dna that codes for a protein

Question 11

what do these proteins do?

Answer 11

they cause you to have different traits. e.g: brown eyes, brown hair etc

Question 12

in the nuclei of your cells, the dna is tightly wound up and condensed into structures called?

Answer 12

chromosomes

Question 13

each chromosome has what?

Answer 13

a different size and a different number of genes

Question 14

chromosomes inherited from your parents are…?

Answer 14

inherited equally (half from each parent)

Question 15

what does every single cell in your body have?

Answer 15

a copy of the same chromosome

Question 16

how many chromosomes in each cell (except the egg and sperm) have?

Answer 16

46

Question 17

How many sets of chromosomes are there and what pair are they found in?

Answer 17

23 sets and they are found in homologous pairs.

Question 18

how many chromosomes do the egg and sperm (sex cells) have?

Answer 18

23

Question 19

what is a cell or organism that contains two copies of every chromosome described as?

Answer 19

a diploid

Question 20

what is a cell or organism that contains only one copy of each chromosome described as?

Answer 20

a haploid

Question 21

what is a karyotype?

Answer 21

a picture of all the chromosomes in a cell.

Question 22

how are karyotypes arranged?

Answer 22

in their homologous pairs and in order of size

Question 23

what are karyotypes used for?

Answer 23

used to see if there are any abnormalities in the number of chromosomes in an organism.

Question 24

what are the first 22 pairs of karyotypes called?

Answer 24

autosomes (non-sex chromosomes) and pair 23 are the sex chromosomes

Question 25

what does 'XX' represent

Answer 25

Female

Question 26

what does 'XY' represent

Answer 26

Male

Question 27

what does 'XX' represent

Answer 27

size, banding pattern and centromere location

Question 28

what does 'centromere location' mean?

Answer 28

the centromere is the centre 'pinch' in the chromosome

Question 29

what are some common abnormalities found in karyotypes?

Answer 29

down syndrome (trisomy 21) turner's syndrome klinefelter's syndrome

Question 30

what is the cause of down syndrome (trisomy 21) and what are some side affects

Answer 30

occurs when there are three chromosome 21's instead of two. can lead to heart and circulatory issues. people with down syndrome often have almond shaped eyes and short limbs

Question 31

what is the cause of turner's syndrome and what are some side affects?

Answer 31

females only have one 'x' chromosome (instead of two, XX). they have short, webbed necks. patients will be unable to have kids.

Question 32

what is the cause of klinefelter's syndrome and what are some side affects?

Answer 32

XXY chromosomes in males (instead of XY). men appear normal, but will be unable to have children.

Question 33

what are allels?

Answer 33

different versions of the same gene.

Question 34

what is a genotype?

Answer 34

particular combination of alleles of a gene (i.e. AA, Aa or aa)

Question 35

what is a phenotype?

Answer 35

the visible expression of a genotype (i.e. brown eyes, blue eyes)

Question 36

what can the phenotype be influenced by?

Answer 36

the environment

Question 37

a trait can either be...?

Answer 37

dominant or recessive

Question 38

what does a dominant trait require?

Answer 38

only one allele before it is shown in the phenotype.

Question 39

How is a dominant trait shown?

Answer 39

shown by a capital letter (i.e AA or Aa)

Question 40

what are some examples of a dominant trait?

Answer 40

brown eyes, rolling the tongue, hitchhikers thumb

Question 41

what does a recessive trait require?

Answer 41

two alleles for it to be shown in the phenotype.

Question 42

how is a recessive trait shown?

Answer 42

shown by a lower case letter (i.e. aa)

Question 43

what are some examples of a recessive trait?

Answer 43

red hair, blue eyes, attached earlobes.

Question 44

what can a genotype be described as?

Answer 44

homozygous dominant (two capital letters): AA, HH, BB heterozygous (two different alleles): Aa, Hh, Bb homozygous recessive (two lower case letters): aa, hh, bb

Question 45

what can someone that is heterozygous for a trait also be called?

Answer 45

a carrier because they carry the allele for the recessive trait (the lower case letter) but don't show it themselves

Question 46

what is a punnet square used to determine?

Answer 46

inheritance

Question 47

what can the punnet square do?

Answer 47

determine the parents genotypes (letter combination) place one genotype along the top of your square and one along the side. write the combination of alleles in each box.

Question 48

what does each box in a punnet square represent?

Answer 48

one possible offspring

Question 49

what is a pedigree?

Answer 49

a family tree diagram that shows the phenotypes of individuals in a family across multiple generations

Question 50

symbols to know.

Answer 50

square (not shaded) = male circle (not shaded) = female square (shaded in) = exhibits trait square (not shaded in) = does not exhibit trait

Question 51

what are roman numerals used for in pedigrees?

Answer 51

used to label generations

Question 52

what are arabic numerals used for in pedigrees?

Answer 52

used to label individuals in each generation

Question 53

what can you do to work out if the trait is dominant or recessive when looking at a pedigree?

Answer 53

1. does it skip a generation? if yes, it is a recessive trait. 2. does an affected child have an unaffected parent? if yes, it is a recessive trait. 3. does every affected child have affected parents? if yes, it is a dominant trait.