Chapter 1 Principles of Life

Question 1

Common characteristics in living organisms is evidence for a common ancestor. What are key common characteristics in living organism?

Answer 1

• common chemical composition
• depend on interactions of complex parts to maintain life
• contain genetic information with nearly universal code for assembly of proteins
• extract energy to carry out life functions
• convert molecules form environment into new biological molecules
• replicate genetic information in same manner for reproduction
• structural similarities in fundamental genes
• evolve through gradual changes in genetic information

*some forms of life don’t show all these characteristics at all times

Question 2

What is endosymbiosis?

Answer 2

Absorption of smaller cells by larger cells. Leading to the formation of organelles

Question 3

How did multicellularity evolve

Answer 3

Arose from one cell failing to divide after replicating. Allowed some cells to specialise in certain functions

Question 4

How does gene replication lead to biodiversity?

Answer 4

Genome replication is imperfect. Each time mutations occur which lead to structural and functional changes in organisms leading evolution of populations over time

Question 5

How are species named?

Answer 5

Named by genus then species

Binomial

Question 6

What are the 3 domains of organisms

Answer 6

Archaea, bacteria and eukaryotes

Question 7

What is the second law of thermodynamics and how does it apply to living organisms?

Answer 7

Organised entities tend to become more random.
Organisation is key for maintaining life (allows organelles andcells to work together), and energy is necessary for maintaining organisation.

Question 8

Describe internal hierarchy

Answer 8

Atom - small molecule - large molecule - cell - cell specialisation - tissue - organ - system - multicellular organism

Question 9

Describe external hierarchy

Answer 9

Population - community - landscape - biosphere

Population: groups of one species living together and interacting
Community: populations of the same or different species in one area
Landscape: multiple communities
Biosphere: entire earth

Question 10

What is a key difference between internal and external hierarchies?

Answer 10

Internal hierarchies are organised by the genome.

External hierarchies are not directed in the same manner and are thus less harmonious

Question 11

Define a system

Answer 11

Set of interacting parts, where neither parts nor the whole can be understood without taking into account the interactions.
Dynamic and constantly exchanging energy and matter with their surroundings and responding to feedback

Question 12

What is the difference between positive and negative feedback?

Answer 12

Positive feedback - product of system ‘speeds up’ an earlier process. Usually destabilises a system
Negative feedback - product of system ‘slows down’ an earlier process. Usually stabilises a system

Question 13

What is the function of system analysis?

Answer 13

Identify components and specify processes by which they interact.
May also specify rates of interactions and how feedback impacts

Question 14

Define genes

Answer 14

Sequence of DNA that carries the information for building or controlling the building of proteins

Question 15

What do proteins do?

Answer 15

Govern chemical reactions within cells to form much of an organisms structure. Made of amino acids

Question 16

How do different cells form different proteins?

Answer 16

By expressing different genes (parts of the genome)

Question 17

How do mutations in the genome occur?

What is the most common impact?

Answer 17

Mistakes in the DNA replication
Certain chemicals (e.g. Cigarette smoke)
Radiation (including UV radiation)

Most mutations are harmful or have no effect

Question 18

What were the first genomes sequenced and when?

Answer 18

First genome sequenced in 1976 - virus
First bacterial genome sequenced 1995
First animal genome sequenced 1998 - roundworm

Question 19

How many different genes are there in the human genome that encode proteins?

Answer 19

21,000

Question 20

What is evolution?

Answer 20

Chang in genetic makeup of populations over time

Question 21

What is natural selection and how does it contribute to evolution?

Answer 21

Concept that some individuals contribute more offspring to future generations than others leading to increase of characteristics of that individual that allowed it to survive longer

Question 22

What are the 2 explanations for adaptations

Answer 22

Proximate explanation - immediate genetic, physical and neurological and behavioural explanation for HOW adaptation works
Ultimate explanation - process that led to adaptation. Involves comparison and variation within species and describes how given traits affect chances of survival and reproduction

Question 23

Explain genetic drift

Answer 23

Changes due to chance event that do not necessarily improve survival

Question 24

Describe the scientific method

Answer 24

Observation - questions - hypothesis - predictions - testing

Question 25

What is the requirement for scientific observations

Answer 25

Must be quantifiable by measurement and mathematical and statistical calculations

Question 26

What is a hypothesis

Answer 26

Possible answer based on information that is already known. Based on observation.

Question 27

What is a controlled experiment?

Answer 27

Experiment manipulating a variable that is predicted to cause the phenomena being tested

Question 28

What is the difference between independent and dependent variables?

Answer 28

Independent - one being manipulated

Dependent - response being measured

Question 29

What is a comparative experiment

Answer 29

One that is looking for differences between samples or groups.
Usually done when variables cannot be controlled

Question 30

Define null hypothesis

Answer 30

Hypothesis that no difference exists between variable

Question 31

What is the purpose of statistical method?

Answer 31

To eliminate the possibility that a result is due to random variation