Unit 7 Chromosomes, genes and DNA

Question 1

chromosome?

Answer 1

a thread like structure made up of DNA. chromosomes carry genetic information in the form of genes

Question 2

mitosis?

Answer 2

mitosis is a type of cell devision where chromosome numbers and genetic composition in the daughter cells remains the same as the mother cell; as there is duplication of DNA

Question 3

Genes?

Answer 3

A length of DNA that codes for a protein. it carries genetic information

Question 4

DNA?

Answer 4

deoxyribonucleic acid- it is a biomolecule (a chemical found in most living organisms) - it is the genetic material found in most living organisms

Question 5

what are the 2 gametes?

Answer 5

Sperm and Ovum/egg

Question 6

what are gametes?

Answer 6

specialised cells for reproduction

Question 7

zygote?

Answer 7

the first cell that is formed after fertilisation or the fusion of male and female gametes

Question 8

order of cells formed after fertilisation

Answer 8

zygote–>embryo–>foetus–>baby

Question 9

haploid?

Answer 9

(half)only 1 set of chromosomes present in a cell

Question 10

diploid?

Answer 10

(double) 2 sets of chromosomes present in a cell

Question 11

XX is what gender

Answer 11

Female

Question 12

who is the baby’s gender dependent on?

Answer 12

the father. because weather the X chromosome is passed down or the Y chromosome is dependent on the paternal chromosomes

Question 13

inheritance?

Answer 13

passing on DNA (as chromosomes containing genes) from parents to offspring

Question 14

“sex inheritance”?

Answer 14

determining the sex of the baby

Question 15

list 5 parts of the sperm cell

Answer 15

acrosome, tail, nucleus, mitochondria, cell membrane, cytoplasm

Question 16

list 3 parts of the egg cell

Answer 16

nucleus, cytoplasm(food reserves) , cell membrane

Question 17

difference between internal and external fertilisation

Answer 17

Internal reproduction takes place inside the body
External reproduction takes place outside the body

Question 18

where does mitosis occur and where does meiosis occur

Answer 18

mitosis occurs in the reproductive cells only while meiosis occurs in all cells except the reproductive cells

Question 19

alleles?

Answer 19

different versions of a gene

Question 20

list examples of alleles for the gene hair colour

Answer 20

• black
• blonde
• brown
• red

Question 21

dominant alleles

Answer 21

always express themselves

Question 22

Recessive alleles

Answer 22

cant express themselves when a dominant allele is present

Question 23

phenotype of this :
Tt

Answer 23

Tall

Question 24

Genotypes if the offspring is tall

Answer 24

Tt or TT

Question 25

genotypic ratio for: 1. TT 2. tt 3. Tt

Answer 25

1. 1:0 2. 1:0 3. 3:1

Question 26

Genotypic ratio for: 1. TT xTT 2. tt x tt 3. Tt x Tt

Answer 26

1. 1:0 2. 1:0 3. 1:2:1

Question 27

if a girl can roll her tongue (T), but her husband cant (t): 1. parents 2. gametes 3. punnet grid 4. offspring

Answer 27

1. Tt x tt or TT x tt 2. T t x t t or T T x t t 3. do in nb 4. ratio of 1:1 cant roll tongue or all offspring call roll their tongue

Question 28

homozygous alleles?

Answer 28

of the same type

Question 29

heterozygous alleles

Answer 29

of different types

Question 30

if PP a purple flowered plant x a white flowered plant: 1. offspring probabilities 2. phenotype 3. genotype

Answer 30

1. 1:0 2. Purple 3. Pp

Question 31

if Pp a purple plant is self-pollinated : 1.offspring probabilities 2.phenotype 3.genotype

Answer 31

1. 3:1 2. 75% purple 25% white offspring 3. PP or Pp or pp

Question 32

if Pp a purple flowered plant x a white flowered plant: offspring probabilities phenotype genotype

Answer 32

1. 1:1 2. 50% chance of white or purple offspring 3. Pp or pp

Question 33

long wing = W short wing = w heterozygous x homozygous recessive: phenotypic ratio? phenotype? genotype?

Answer 33

1. 1:1 2. 50% either short or long 3. Ww or ww

Question 34

Long hair = H short hair = h heterozygous x heterozygous: punnet square phenotypic ratio genotypic ratio phenotype genotype

Answer 34

1. in nb 2. 3:1 3. 1:2:1 4. 75% long hair 25% short hair 5. HH or Hh or hh

Question 35

does the length of the chromosomes get shorter or longer?

Answer 35

shorter with the first set being the longest, the second set being second longest and so on

Question 36

why cant we usually see chromosomes even with microscopes?

Answer 36

chromosomes only become visible with a light microscope when a cell is dividing and also need to be coloured using special stains

Question 37

does RBC have chromosomes?

Answer 37

no because it doesn't have a nucleus