Chapter 1. Studying Life

Question 1

What is biology?

Answer 1

It is the scientific study of organisms regardless of whether the organisms are living or not living (e.g. fossils)

1.1 Living Organisms Share Similarities and a Common Origin

Question 2

What are the characteristics of a living organism?

Answer 2

• Made of similar chemical compounds like fatty acids, carbohydrates, nucleic acids and amino acids.
• Composed of cells
• use molecules from the environment to make other molecules
• Able to extract energy from the environment and use it for activities
• Contain genomes
• Use a universal molecular code for constructing proteins
• Able to regulate their internal environment, This is called homeostasis
• Part of populations that can adapt/evolve over time.

1.1 Living Organisms Share Similarities and a Common Origin

Question 3

Prokaryotic archaea and bacteria are ________

Unicellular/multicellular

Answer 3

Unicellular

1.1 Living Organisms Share Similarities and a Common Origin

Prokaryotic archaea (yellow); bacteria (pink)

Question 4

Protists have less complex cell structures than prokaryotic archaea and bacteria?

True/False

Answer 4

False

Protists have more complex cell structures than prokaryotic archaea and bacteria?

1.1 Living Organisms Share Similarities and a Common Origin

Protists (blue)

Question 5

State a logical explanation for the striking similarities of living organisms on Earth?

Answer 5

All living organisms on Earth share a common ancestor (one living organism) that lived about 4 billion years ago.

1.1 Living Organisms Share Similarities and a Common Origin

Question 6

Just a useful 30-day calendar on the back of this flashcard, no questions to answer.

Answer 6

1.1 Living Organisms Share Similarities and a Common Origin

Question 7

How long did it take for the earth to cool, become home to the first life forms and develop surface water (Oceans, lakes, rivers etc.)

Answer 7

About 600 million years. The Earth was formed approx 4.6 billion years ago and the first life forms evolved 4 billion years ago. Earth could not have been habitable to these first life forms if it was not cool and did not have surface waters.

1.1 Living Organisms Share Similarities and a Common Origin

Question 8

State some important steps for the evolution of life

Answer 8

• The appearance of nucleic acids that could help construct proteins
• The evolution of cell membranes

1.1 Living Organisms Share Similarities and a Common Origin

Question 9

When a film of fatty acids is agitated it can form a spherical shape called a ________. _________ are now used to deliver drugs to cells.

Answer 9

liposomes

1.1 Living Organisms Share Similarities and a Common Origin

see image of liposome

Question 10

What is a key benefit of having a cell membrane?

Answer 10

A cell membrane helps keeps many molecules of products and reactants of a chemical reaction in a tiny environment and so the chemical reaction is more likely to happen and increases the rate of the chemical reaction.

1.1 Living Organisms Share Similarities and a Common Origin

Question 11

The first life forms on Earth were unicellular/multicellular and were eukaryotic/prokaryotic

Answer 11

Unicellular; prokaryotic

1.1 Living Organisms Share Similarities and a Common Origin

Question 12

What is a prokaryotic organism?

Answer 12

An organism that is single-celled and does not have internal membranes surrounding organelles (including a nucleus). It only has an outer membrane.

1.1 Living Organisms Share Similarities and a Common Origin

Question 13

Which two of the three: Archaea, Bacteria, Eukarya are prokaryotic?

Answer 13

Archaea and Bacteria

1.1 Living Organisms Share Similarities and a Common Origin

Question 14

Which of the two (bacteria and Archaea) have peptidoglycan in their cell walls

Answer 14

Bacteria

1.1 Living Organisms Share Similarities and a Common Origin

Question 15

What is meant by eukaryotic cells?

Answer 15

Eukaryotic cells have one large outer membrane and some internal membranes enclosing organelles.

1.1 Living Organisms Share Similarities and a Common Origin

Question 16

How might eukaryotes have arisen from prokaryotes?

Answer 16

The membranes of prokaryotes may have infolded to give membrane-bound organelles.

Another possibility is that prokaryotic cells formed an interdependent relationship with each other

1.1 Living Organisms Share Similarities and a Common Origin

Question 17

Describe how prokaryotes supply their energy needs

Answer 17

Prokaryotes take molecules from the environment and break the bonds between atoms within these molecules. This releases which the prokaryotes can use to fuel cellular activities. Such cellular activities could be forming large molecules from simple molecules.

1.1 Living Organisms Share Similarities and a Common Origin

Question 18

When is photosynthesis thought to have evolved?

Answer 18

2.5 billion years ago

1.1 Living Organisms Share Similarities and a Common Origin

Question 19

Which organism is credited for the accumulation of oxygen in Earth’s atmosphere

Answer 19

Cyanobacteria

1.1 Living Organisms Share Similarities and a Common Origin

Question 20

How are Stromatolites formed?

Answer 20

They are formed by communities of microorganisms (such cyanobacteria) that cement grains of sediment together.

1.1 Living Organisms Share Similarities and a Common Origin

Question 21

Do you think there was any oxygen in the Earth’s atmosphere before the evolution of photosynthesis 2.5 billion years ago?

Answer 21

No - there was no oxygen in the atmosphere before the evolution of photosynthesis 2.5 billion years ago.

1.1 Living Organisms Share Similarities and a Common Origin

Question 22

The accumulation of oxygen was not toxic to obligate anaerobes and so there was no mass extinction event

True/False

Answer 22

False

Oxygen was toxic to obligate anaerobes and the oxygen rich atmosphere did cause a mass extinction event called the oxygen catastrophe.

1.1 Living Organisms Share Similarities and a Common Origin

Question 23

Which of the two processes were more efficient than the other?

Anaerobic metabolism or aerobic metabolism

Answer 23

aerobic metabolism

1.1 Living Organisms Share Similarities and a Common Origin

Question 24

Explain how oxygen in the atmosphere helped organisms move from water to land.

Answer 24

Photosynthetic cyanobacteria produced enough oxygen in 2 billions to produce a thick dense ozone layer (O ₃). This Ozone layer would absorb UV radiation from the sun

Question 25

What is the genome of an organism?

Answer 25

It is the full sequence of all the DNA contained in the cells of an organism.

1.1 Living Organisms Share Similarities and a Common Origin

Question 26

A useful picture is on the back of this flashcard that summarises a whole paragraph of text on page 5 of the Life (11th edition) book

Answer 26

1.1 Living Organisms Share Similarities and a Common Origin

Question 27

State some ways mutations can occur in the genome of organisms

Answer 27

• By DNA replication - DNA replication isn’t perfect
• By some chemicals
• By radiation

1.1 Living Organisms Share Similarities and a Common Origin

Question 28

In what three ways can a mutation affect an organism

Answer 28

1. It could be harmful to the organism.
2. It may have no effect on the organism.
3. It may even improve the organism’s fitness to its environment.

1.1 Living Organisms Share Similarities and a Common Origin

Question 29

What is a population?

Answer 29

A population is a group of the same type of organism that interbreeds.

Question 30

How was the phrase “natural selection” coined

Answer 30

Darwin thought that if humans can select desired traits in plants and animals (artificial selection) then maybe nature could operate in the same way. He called it natural selection.

Question 31

Arrange the following terms from largest to smallest to create a hierarchy of biological organization

Atoms, Molecules, Organism, Biosphere, Cells, Ecosystem, Population and Community

Answer 31

1. Atoms
2. Molecules
3. Cells
4. Organism
5. Population
6. Community
7. Ecosystem
8. Biosphere