Evolution

Question 1

Evolution

Answer 1

the process of cumulative change in the heritable characteristics of a population

Question 2

Speciation

Answer 2

is the process by which new species form. It occurs when groups in a species become reproductively isolated and diverge.

Question 3

Evidence for evolution by natural selection

Answer 3

1) Fossil Record
2) Animal breeding
3) homologous structures
3) Vestigial Structures
4) Selective breeding
5) Observable change

Question 4

Homologous structures

Answer 4

organs or skeletal elements of animals and organisms that, by virtue of their similarity, suggest their connection to a common ancestor

Question 5

Fossil record

Answer 5

accumulation of evidence from the remains and traces such as skeletons and footprints

Question 6

Ageing Fossils

Answer 6

Age of a rock can be determined by examining the differences in the ratio of isotopes. fossil with a higher level of Carbon-14 is younger than a fossil with lower C-14.Because C-14 is radioactive and it slowly loses its radioactivity.It changes into Nitrogen-14.Its called Radioactive decay.

Question 7

Radioactive decay

Answer 7

Radioactive parent isotope changing into a stable daughter isotope.

Question 8

Half life

Answer 8

Speed at which radioactive decay happens. Time it takes for half of the parent isotope to decay into a stable daughter isotope.

Question 9

Examples of homologous structures

Answer 9

5-fingered limb found in animals such as humans, whales, brats .they are called PENTA-DACTYL. The shape and no of bones may vary, the general format is the same.Whales could swim well with a different number of fingers in their front fins.Suggests common ancestry.

Question 10

More info on homologous structures

Answer 10

Different sizes, Varied morphology(shape), basic shape and position of the limb bones are the same.

Question 11

Adaptive Radiation

Answer 11

Rapid evolution of diversely adapted species from a common ancestor when a change in environment makes new resources available, creates new challenges, open new environmental niches.

Question 12

Adaptive radiation effects

Answer 12

1) Mass Extinctions
2) Evolution of novel characteristics
3) Colonization of new habitats

Question 13

Examples of Adaptive radiation

Answer 13

1) Darwin Finches: Darwin found variety of bird on Galapagos islands that were very closely related to each other.Each uniquely suited to the different islands they were on.They all had different shape of beaks to adapt to the food source.They were originally derived from a common mainland ancestor.
2) Hawaiian honey creepers: have variety of beak shapes some of which are adapted to sip the nectar of flowers found only on Hawaii.

Question 14

Polymorphism

Answer 14

A polymorphism is the occurrence of two or more clearly different phenotypes within the same population of a species - it reflects the effects of more than one allele in the gene pool

Question 15

Transient Polymorphism

Answer 15

A situation when there are two alleles in a gene pool (polymorphic) and one allele is gradually replacing another
This is due to a strong environmental selective pressure causing directional selection to eliminate one allele

Question 16

Example of Transient Polymorphism

Answer 16

There are two types of these moths; one species has a light color while the other one is darker. When Britain begun industrializing, the soot from the factories would land on trees and so the darker moths then had an advantage over the light ones as they could easily hide from predators. Before the soot, both types of moths were eaten by predators however now that the darker ones were able to hide the lighter ones got eaten more often. The population of the darker moths rapidly increased while that of the lighter ones rapidly decreased until only the dark moths were left. All the lighter moths were less adapted to the environmental change and so they could no longer survive in that new environment.

Question 17

What is Natural Selection ?

Answer 17

1) Discovered by Charles Darwin
2) Mechanism for evolution
3) Organisms that are more adapted to their environment are more likely to survive and pass on the genes that aided their success. This process causes species to change and diverge over time.

Question 18

Definition of Natural selection

Answer 18

Natural selection is a process where organisms that are better adapted to an environment will survive and reproduce. This means that the advantageous alleles of this variant organism are passed on to offspring. Over many generations, the process of natural selection leads to evolution occurring

Question 19

Species

Answer 19

A biological species is a group of organisms that can reproduce with one another in nature and produce fertile offspring.

Question 20

Mutation

Answer 20

Any change in the DNA of an organism that can impact the basic genetic information of a living being.

Question 21

Significance of mutation

Answer 21

1) Evolution is based on mutation

2) It causes variation

Question 22

Disadvantages of Mutation

Answer 22

1) Leads to uncontrolled growth of cells-Cancer
2) Causes several other diseases- Down syndrome
3) Sickle cell diseases is caused by mutation.

Question 23

Causes of mutation

Answer 23

1) Genetic:Mutation passed on by ancestors, Germ line mutations. Transferred through gamete cells/sex cells
2) Environmental: (Not transferred to the next generation), caused by physical factors, chemicals, smoke, also called as somatic mutation

Question 24

Meiosis

Answer 24

1) Causes genetic variation

2) Divided into 2 parts: Meiosis 1, Meiosis 2

Question 25

How does meiosis and fertilization bring about genetic variation

Answer 25

1)Crossing over at pro phase 1: Genetic material swapped between maternal and paternal chromosomes., New genetic combination of alleles

2) Independent assortment of homologous chromosomes at meta phase 1
3) Independent assortment of chromatids at meta phase 2.
4) Production of haploid gametes that fuse randomly at fertilization.

Question 26

Alleles

Answer 26

1) Varieties of a genes
2) Typically represented by letters
3) lowercase= Recessive allele, cant be expressed
4) Uppercase=Dominant allele, is expressed

Question 27

Phenotype

Answer 27

Physical characteristics

Question 28

Antibiotics

Answer 28

Antibiotics kill bacteria directly or weaken the bacteria so your immune system can fight and destroy the invading pathogen.

Question 29

Resistance Against Antibiotics

Answer 29

1) Some of these bacteria might not die because of changes within their DNA. These changes could be caused by mutations within their genome or the transfer of an antibiotic-resistant gene from another bacterium.
2) These resistant bacteria will survive and reproduce, creating more identical resistant bacteria.
3) Eg: the bacteria that causes tuberculosis (Mycobacterium tuberculosis)

Question 30

Disruptive Selection

Answer 30

Individuals with either extreme variation of a trait have greater fitness than individuals with the average form of trait

Question 31

Environmental factor increasing gene mutation

Answer 31

1) Radiation
2) Carcinogens
3) Cigarette smoke
4) Chemical mutagens

Question 32

Types of Gene mutations

Answer 32

1) Frame shift mutation : This type of mutation occurs when the addition or loss of DNA bases
changes a gene’s reading frame. A reading frame consists of groups of
3 bases that each code for one amino acid. A frame shift mutation shifts
the grouping of these bases and changes the code for amino acids. The
resulting protein is usually nonfunctional.
2) Deletion: A deletion changes the number of DNA bases by removing a piece of DNA.
3)Insertion: An insertion changes the number of DNA bases in a gene by adding a piece
of DNA