Bio

Question 1

Alleles

Answer 1

Alleles are alternate forms of a gene. Alleles control the contrasting characteristics of each trait. Alleles can either be dominant or recessive.

Question 2

Dominant alleles

Answer 2

Dominant alleles are symbolised by capital letters. A dominant allele will always express (show) itself.

Question 3

Recessive alleles

Answer 3

Recessive alleles will only express themselves in the absence of dominant allele. Recessive alleles are symbolised by lower case letters.

Question 4

Genotype

Answer 4

The genetic makeup (combination of alleles) of an organism.

Question 5

Phenotype

Answer 5

• The physical features/appearance of an organism

Question 6

Homozygous

Answer 6

Homozygous means an organism has two identical alleles for a trait. Example : BB, bb

Question 7

Heterozygous

Answer 7

Heterozygous means an organism has two different alleles for a trait. Example: Bb

Question 8

Inheritance of Sex

Answer 8

females have two X chromosomes. Each ovum produced through meiosis will contain one X chromosome. males have one X and one Y chromosome. When sperm are produced through meiosis, they will contain either an X chromosome or a Y chromosome.

Question 9

Genetic Traits Carried on Sex-Chromosomes

Answer 9

The Y chromosome is shorter than the X chromosome so it has fewer genes. Some genes on the X chromosome do not have a corresponding gene on the Y chromosome. Due to this, some genetic traits are more common in males than in females.

Question 10

Pedigrees

Answer 10

A pedigree is a pictorial representation of the pattern of a genetic trait or condition in a family. Males are drawn as squares. Females are drawn as circles. Individuals with the trait are shaded.

Question 11

Co-dominance

Answer 11

• Co-dominance is a form of inheritance where two or more alleles are equally dominant. This means that if both alleles are present, they will both be expressed in the resulting phenotype.

Question 12

Genetic Mutation

Answer 12

A mutation is a permanent change in the DNA sequence. Mutations can occur in one or more genes.

Question 13

Mutagens

Answer 13

Mutations occur naturally, but some factors can increase the chance of mutations occurring. Such as, Radiation, Chemicals, UV light

Question 14

Negative Mutations from Radiation

Answer 14

Exposure to radiation can cause cancers and birth defects.

Question 15

Variation

Answer 15

Some naturally occurring mutations lead to the production of new alleles. These new alleles lead to a more diverse gene pool and variation within a species.

Question 16

Adaptations

Answer 16

A small number of these mutations may lead to adaptations, Animals that develop adaptations more suited to survival are more likely to live, and therefore more likely to pass on their genes

Question 17

Species

Answer 17

the largest group of organisms in which any two individuals can produce fertile offspring

Question 18

Natural Selection

Answer 18

Natural selection is the process by which individuals that are best suited to their environment pass on their genes. This theory was proposed by Charles Darwin

Question 19

Gene Pools

Answer 19

All species have limited alleles that exist in a population. The gene pool includes all the alleles for all the genes in that population. When new mutations arise, alleles are introduced to this gene pool and the gene pool will increase.

Question 20

Allele Frequency

Answer 20

Allele frequency is how common an allele is in a particular population.

Question 21

Speciation

Answer 21

Speciation is the process by which one species splits into two or more separate species. The process of speciation occurs in three steps: Variation, Isolation, Selection.

Question 22

Step 1: Variation

Answer 22

A few genetic mutations produce new alleles, which result in new traits. These new traits make the population more diverse. This is called variation.

Question 23

Step 2: Isolation

Answer 23

Isolation happens when different groups within a population are somehow prevented from interbreeding. There are two main ways in which this occurs: Geographical barriers and Climatic barriers.

Question 24

Step 3: Selection

Answer 24

Each group is exposed to selection pressures, such as: Food / shelter availability, Environmental conditions, Biological factors (predators, diseases etc.) Over time, the groups become less and less alike. Eventually, the two groups become so different that they cannot mate any more and the two are considered different species.

Question 25

Theory of Evolution

Answer 25

All species share a common ancestor and gradually change over time due to the process of natural selection.

Question 26

Convergent Evolution

Answer 26

Two or more different species are exposed to similar selection pressures. They develop different structures to perform a similar task. These are known as analogous structures.

Question 27

Divergent Evolution

Answer 27

A single species evolves into two or more different species through speciation. These different species retain some characteristics of their common ancestor. These are known as homologous structures.

Question 28

Evidence for Evolution

Answer 28

The Theory of Evolution was developed based on a large collection of evidence: Fossil record, Embryology, Comparative anatomy, DNA and protein similarities

Question 29

Fossil Record

Answer 29

Through the use of carbon dating the age of fossils can be determined.

Question 30

Embryology

Answer 30

Vertebrates become wildly different as they age, but during the early stages of development they are quite similar. These similarities suggest that these organisms all had a common ancestor.

Question 31

Homologous structures

Answer 31

Similar structures in different organisms

Question 32

Vestigial structures

Answer 32

Functionless structures found in organisms, which help provide evidence of evolution, as these structures were once useful to the organism

Question 33

DNA and Protein Similarities

Answer 33

The more similar the DNA and protein structures, the more closely related the species are.

Question 33

Artificial Selection

Answer 33

Artificial selection occurs when humans increase the breeding and reproduction of organisms that have desirable traits. artificial selection increases desirable traits in future generations

Question 34

Cross-Breeding

Answer 34

Cross-breeding is the process of breeding an individual with a particular, desirable trait with an individual with a different desirable trait.

Question 35

In-Breeding

Answer 35

In this process, related individuals are allowed to mate.

Question 36

Benefits of selective breeding

Answer 36

Animals can be selected for desirable physical traits or
behaviours.

Question 37

Risks of selective breeding

Answer 37

Can create physical problems in specific organisms