Evolution Stage 2 Biology

Question 1

Population

Answer 1

a group of the same species that interbreed in a particular community. One species can consist of several populations which are isolated from one another.

Question 2

Gene pool

Answer 2

total set of genes that are found in an interbreeding population. All members of the species contribute to the genetic makeup of the gene pool.

Question 3

Gene pools of different species…

Answer 3

remain isolated as the members of different species do not interbreed and have fertile offspring.

Question 4

Asexual Reproduction

Answer 4

organisms that produce offspring that don’t involve the production of sperm and eggs undergo asexual reproduction.

• definition of interbreeding don’t apply

Question 5

Pre-zygotic mechanisms prevent…

Answer 5

reproduction before the zygote is formed.

Question 6

Temporal (Time) Isolation

Answer 6

Breeding cycles or time of fertility differs from one population of species to the next.

Question 7

Ecological Isolation

Answer 7

Ecological, habitat or ecological isolation occurs when two species that could interbreed do not because the species live in different areas.

Question 8

What features do living things share?

Answer 8

Cell membrane composed of lipids

RNA and DNA

Proteins composed of the same amino acids
Water composition by mass is 50%-80% for all cells and water has the same functions in all cells.

Question 9

The Oldest identifiable evidence of prokaryotes dates back too…

Answer 9

3.5 million

Question 10

The Oldest identifiable evidence of eukaryotes dates back too…

Answer 10

2.7 million

Question 11

Cyanobacteria

Answer 11

• formed stromatolites
• are photosynthetic
• important for evolution on earth as they released oxygen into atmosphere.

Question 12

What processes were thought to be necessary for life to begin?

Answer 12

Synthesis of:

• simple organic molecules e.g. amino acids and synthesis of
• larger organic polymers e.g. proteins

The origin of molecules that can self replicate. I.e. RNA and DNA.

Packaging of these molecules into membranes with an internal environment different in composition from their surroundings.
These structures are known to form spontaneously.

Question 13

RNA World Hypothesis

Answer 13

proposes that a world filled with RNA-based life predates current DNA-based lifeforms.

Question 14

RNA World Hypothesis - RNA can self-replicate

Answer 14

RNA is able to store information in a sequence composed of four recurring nucleotides (similar to DNA)

Short sequences of RNA are able to be accurately duplicated to form identical RNA molecules.

Question 15

RNA World Hypothesis - RNA can act as a catalyst

Answer 15

Modern cells use RNA catalysts (called ribozymes) to remove introns from mRNA and help synthesise new RNA molecules

In ribosomes, rRNA functions as the catalytic component and plays a pivotal role in peptide bond formation

Question 16

It is believed that prokaryotes evolved before…

Answer 16

eukaryotes

Question 17

Evidence support eukaryotes evolved second: Fossils

Answer 17

Fossils: earliest eukaryote fossil found, a multicellular alga – 2.1 billion years old

Question 18

Evidence support eukaryotes evolved second: Biomarkers

Answer 18

Biomarkers – eukaryotic biomarkers have been found in sedimentary rocks in the Earth’s crust indicating 2.7 billion years ago. (Sterols – a molecule only found in eukaryotic membranes)

Question 19

Evidence support eukaryotes evolved second: Comparison of structure

Answer 19

DNA in eukaryotes has a higher level of organization

Eukaryotes have membrane bound organelles

Eukaryotic cells are bigger

Question 20

The oldest and most primitive eukaryotes are called…

Answer 20

Protists.

Question 21

It is believed that eukaryotic cells probably originated as a collection of…

Answer 21

prokaryotes.

Question 22

The formation of eukaryotes: Step 1

Answer 22

The first step involved folding of the membrane to form the endo-membrane system. This step is thought to have formed the endoplasmic reticulum and most other organelles.

Question 23

The formation of eukaryotes: Step 2

Answer 23

The second step was the process of endosymbiosis. Chloroplasts and mitochondria seemed to have evolved from prokaryotes which became incorporated after being engulfed by another cell.

Question 24

Evidence supporting the formation of eukaryotes process.

Answer 24

mitochondria and chloroplasts have inner membranes similar to plasma membranes of prokaryotes, they replicate by splitting through binary fission, they have their own circular DNA and have their own protein manufacturing system including ribosomes.

Question 25

Evolution

Answer 25

the change in heritable characteristics of biological populations over successive generations.

Question 26

Evolution can be recognized and measured using changes in…

Answer 26

the structure or base sequence of DNA.