YR11 - Topic Test - Mendelian Inheritance

Question 1

Genotype

Answer 1

The total set of genes of an organism. The combination of alleles for a trait to be carried by an individual.

Question 2

Phenotype

Answer 2

An observable trait or character of an organism. The overall appearance of an organism.

Question 3

Allele

Answer 3

One of the alternative forms of a gene. Most genes have 2 alleles, but more than two alleles are possible.

Question 4

Dominance

Answer 4

The expression of 1 allele of a gene rather than another allele of the same gene. (covers recessive trait)

Question 5

Recessive

Answer 5

Relating to a trait or phenotype (encoded by an allele or gene) whose appearance is subordinate to a dominant trait.

Question 6

Genome

Answer 6

The DNA in one full set of chromosomes present in the nuclei of normal cells of a species.

Question 7

Eukaryotic

Answer 7

An organism whose cells contain a membrane-bound nucleus and other membrane-bound organelles.
e.g. animals, plants, fungi etc.

Question 8

Prokaryotic

Answer 8

An organism with cells that do not have a membrane-bound nucleus and lack most organelles.
All prokaryotes are bacteria

Question 9

Human Genotype Project

Answer 9

A worldwide project started in 1990 to determine the human genome, the precise order of nucleotides within a DNA molecule and the number of genes in one human individual

Question 10

HGP advantages and ethical considerations

Answer 10

ADVANTAGES

• Predict and prevent diseases changes.
• Improved medicine
• Accurate diagnoses
• Improve forensic science

ETHICAL CONSIDERATIONS

• Informed consent is critical
• Protect patient confidentiality

Question 11

Structure of Nucleotide

Answer 11

Phosphate
Pentose-Sugar
4 Nitrogen-containing bases

Question 12

Nucleotide

Answer 12

Nucleotides are the building blocks of nucleic acids such as DNA and RNA.

Question 13

Complementary base pairings

Answer 13

Adenine - Thymine

Guanine - Cytosine

Question 14

Hydrogen bonding between complementary DNA strands

Answer 14

Hydrogen bonds are located between the complementary base pairs to help join them together

Question 15

The effect of heating and cooling on the hydrogen bonds

Answer 15

Heating hydrogen bonds =
When the heat is raised (for instance, as water is boiled), the higher kinetic energy of the water molecules causes the hydrogen bonds to break completely and allows water molecules to escape into the air as gas

Cooling hydrogen bonds =
When water is cooled, the molecules begin to slow down

Question 16

DNA coiling into chromosomes

Answer 16

In the nucleus of each cell, the DNA molecule is packaged into thread-like structures called chromosomes. Each chromosome is made up of DNA tightly coiled many times around proteins called histones that support its structure.

Nucleosomes help stop the DNA from breaking, but the genes in DNA can still be accessed to make proteins

Question 17

Coiling DNA

- chromatid vs condensed chromosomes

Answer 17

Chromatid - are short and fat
- like cooked spag (easy to break)

Condensed Chromosome - less likely to break during anaphase of mitosis/meiosis
- like cooked penne (much thicker, not as easy to break)

Question 18

Karyotypes

Answer 18

A visual depiction of the number, size and shape of chromosomes in an individual.

Question 19

Monosomy

Answer 19

A condition in which part of all or 1 chromosome of a particular diploid pair is missing in a karyotype.
e.g. turner syndrome

Question 20

For humans, the term nuclear genome refers to all the genes in

Answer 20

a set of autosomes plus the sex chromosomes.

Question 21

Trisomy

Answer 21

An abnormality in which a cell has 3 copies of a particular chromosome
e.g. trisomy of chromosome 21 which causes down syndrome in humans

Question 22

Non-disjunction

Answer 22

the failure of homologous chromosomes or sister chromatids to separate properly during cell division.

Question 23

Monohybrid cross

Answer 23

A cross between individuals that have different pairs of alleles of a particular gene
e.g. 1 individual might have T and t alleles, the other might have t and t alleles

Monohybrid crosses are used to study the inheritance of 1 characteristic

Question 24

Dihybrid cross

Answer 24

A cross between pure lineages that exhibit 2 different phenotypes.
e.g. a cross between a pea with dominant phenotypes of yellow seeds and red flowers, and a pea with recessive phenotypes of green seeds and white flowers

Question 25

Sex-linked inheritance

Answer 25

Inheritance related to genes that occur on the sex chromosomes (X and Y).
e.g. red-green colour blindness, which is caused by a mutation in a gene on the X chromosome

Question 26

Test cross

Answer 26

A type of backcross in which an individual with the dominant phenotype is crossed with an individual of a recessive phenotype for the character being studied

Question 27

Multiple alleles

Answer 27

Most genes have 2 alleles (dominant/recessive) e.g. hairline trait
but..
some genes have more than 2 alleles e.g. blood group

Question 28

Co-dominance

Answer 28

The occurrence of a phenotype in a heterozygous that results from the expression of both alleles
e.g. the AB blood group of humans

Question 29

Trait

Answer 29

A particular characteristic or feature of an organism

Question 30

Monogenetic inheritance

Answer 30

Monogenic inheritance refers to the kind of inheritance whereby a trait is determined by the expression of a single gene or allele, not by several genes as in polygenic inheritance.
e.g. hairline, blood type, earlobes

Question 31

Eukaryotic genome

Answer 31

• DNA in nucleus
• membrane-bound organelles
  e.g. mitochondria (tiny bit of dna)
  chloroplast (tiny bit of dna)

Question 32

Eukaryotic genome

Answer 32

• DNA in nucleus
• membrane-bound organelles
  e. g. mitochondria (tiny bit of dna)

chloroplast (tiny bit of dna) ONLY in plant cells

Question 33

Polygenetic inheritance

Answer 33

The inheritance of an observable trait that is determined by many genes.
e.g. height, weight, hair and eye colour etc.

Question 34

Continuous variation

Answer 34

Polygenetic traits - because there is a greater variation between individuals

Question 35

Discontinuous variation

Answer 35

Monogenetic traits - because only a few genes control the trait and doesn’t allow much variation

Question 36

Autosome

Answer 36

Chromosomes that are not sex chromosomes