Darwins Ideas

Question 1

Natural Selection

Answer 1

The process where organisms better adapted to their environment tend to survive and produce more offspring, passing on favourable traits

Question 2

Artificial selection

Answer 2

The process where humans choose organisms with desirable features and selectively breed them together to enhance through traits over time

Question 3

How did Darwin get to natural selection?

Answer 3

Started with artificial selection and compared human agriculture with nature

Question 4

Darwins argument for natural selection

Answer 4

• Individuals with advantageous traits are surviving, so this must be occurring without humans choosing traits
• these traits accumulate in the population, explaining how species adapt to changing environments

Question 5

Example of natural selection

Answer 5

Peppered moth example
-mimics lichen on trees, camouflage
- when moths didnt match their background they were more likely to get eaten
- when extreme polluting ban was put in place, less coal so less environment for black moths to stay hidden

Question 6

3 types of selection

Answer 6

Directional, disruptive, stabilizing

Question 7

Directional selection

Answer 7

selection for one extreme

Question 8

Disruptive selection

Answer 8

selection for the extremes only

Question 9

Stability selection

Answer 9

selecting against the extremes

Question 10

Darwins fitness

Answer 10

physical ability, speed, strength, smarts

Question 11

mathematical fitness

Answer 11

number of offspring per lifetime that survive to reproductive age

Question 12

Anti-biotic resistance (natural selection)

Answer 12

• non-resistant bacteria exists and multiples
• a mutation makes bacteria resistant, which multiples and thrives

Question 13

Why was natural selection controversial?

Answer 13

argued that it couldn’t be applied to a larger scale, that the mechanisms for heredity were unknown, and that there wasn’t enough time for this type of change to occur

Question 14

complex scale explanation and Darwins response

Answer 14

using the eye
- extremely complex and developed, so could be seen as a sign of a great creator, like God
Darwins Response: if variations in light detecting structures were beneficial and inherited, giving advantages, then natural selection would be gradually improving to a more function eye

Question 15

Homology

Answer 15

similar structure with different forms in different species

Question 16

Homology/change in function example

Answer 16

Orchid
- lots of variations depending on the selection pressures and similar structures have been modified to suit the ecological niche

Question 17

Blending inheritance

Answer 17

theory suggesting that offspring inherit traits as a mix or blend of their parents’ traits

Question 18

What is the issue with blending inheritance?

Answer 18

new traits that appear will be blended and become insignificant, and this would not work if traits are continuous

Question 19

Mutationism

Answer 19

observation of ‘sports’ rare variants
- inheriting traits in a discrete way, leading to bigger jumps in evolution

Question 20

Pangenesis

Answer 20

idea suggesting that our bodies have small particles called gemmules that are sent to reproductive cells and transmitted to the next generation
not a correct theory

Question 21

Modern view on Pangenesis

Answer 21

follows Mendel’s idea

Question 22

Lamarckism

Answer 22

idea that evolution could work through the inheritance of acquired characteristics

Question 23

How was Lamarckism debunked?

Answer 23

biologists discovered sex cells with chromosomes to see mitosis and that not all cells were passed down, so hereditary particles are in those cells

Question 24

George Mendel

Answer 24

discovered the fundamental principle of inheritance by crossing peas to show how traits are passed down from parent to offspring in predictable patterns based on genetics

Question 25

F1

Answer 25

filial 1, first generation cross

Question 26

F2

Answer 26

filial 2, second generation cross

Question 27

allele

Answer 27

variation of a gene

Question 28

Eclipse of Darwinism

Answer 28

- biometricians argued for a 'smooth' evolution of continuous characters, but Mendelians believed in sudden evolution by mutation

Question 29

Are traits continuous of discrete?

Answer 29

Polygenetic inheritance and modern synthesis - showed that continuous traits are combinations of many discrete alleles

Question 30

Polygenetic

Answer 30

multiple genes contribute to the characteristic

Question 31

Where does variation come from?

Answer 31

DNA - unique combinations of base pairs in genes code for different phenotypes

Question 32

Mendels law of segregation

Answer 32

traits are determined by 2 alleles, which segregate independently due to meiosis separating chromosomes

Question 33

Mendels law of independent assortment

Answer 33

alleles of different traits sort independently due to being on different chromosomes

Question 34

How is genetic information transferred?

Answer 34

copying through DNA replication

Question 35

DNA replication process

Answer 35

1. DNA unwinds 2. Enzymes create new strands based on old strands base pairs 3. 2 complete strands form

Question 36

Semi-conservative

Answer 36

each complete DNA strand has a new and old strand

Question 37

Types of mutations

Answer 37

Transition, transversion, insertion, deletion

Question 38

Transition mutation

Answer 38

when a purine/pyrimidine is replaced by another pruine/pyrimidine

Question 39

Transversion mutation

Answer 39

when a purine is replaced by a pyrimidine or vice versa