Classification And Evolution

Question 1

What is classification?

Answer 1

It is the name given to the process by which living organisms are sorted into groups

Question 2

What is the name of the classification system used by scientists?

Answer 2

The “Linnaean classification system” proposed by Carl Linnaeus in the 1700s

Question 3

What are the 8 taxonomic groups?

Answer 3

They are Domain, kingdom, phylum, class,order,family,genus and species

Question 4

Why do scientists classify organisms?

Answer 4

•To identify species and organism belongs to
• To predict characteristics
• To find evolutionary links- species in the same group probably share similar characteristics because they have evolved from a common ancestor

Question 5

What is a species?

Answer 5

Species are defined as a group of organisms that are able to reproduce to produce fertile offsprings

Question 6

What is Binomial nomenclature?

Answer 6

It is a system that is used to name organisms so that scientists all over the world know what organisms that are referring to during discussions

Question 7

How to name organisms using the Binomial nomenclature?

Answer 7

The first word indicates the organism’s genus which is written in capital letter and the second word indicates the organism’s species which is written in lowercase letter

Question 8

How were organisms originally classified into?

Answer 8

Organisms were originally classified based on two features, whether they moved(animals) or didn’t (plants)

Question 9

What are the 5 kingdoms?

Answer 9

Protoctista
Prokaryota
Animalia
Plantae
Fungi

Question 10

Who introduced the 5 kingdom classification system?

Answer 10

Robert Whittaker who was an American plant ecologist and he based it on the principles developed by Carl Linnaeus

Question 11

Features of prokaryotae

Answer 11

1. Circular DNA not wrapped around histone proteins
2. They are unicellular
3. They have no nucleus, nor membrane bound organelles
4. They get their nutrients either by absorption through the cell wall or by photosynthesis
5. They have small 70S ribosomes

Question 12

Features of protoctista

Answer 12

1. (mainly) Unicellular
2. A nucleus and other membrane bound organelles
3. Some have chloroplast
4. Some move either with the aid of cilla and flagella or by amoeboid movement
5. Nutrients are acquired through photosynthesis (autotrophic feeders), ingestion of other organisms(heterotrophic feeders) or both- some are parasitic

Question 13

Features of fungi

Answer 13

1. Unicellular or multicellular
2. They are saprophytic feeders- nutrients are acquired by absorption mainly from decaying material
3. No chloroplasts or chlorophyll
4. A nucleus and other membrane bound organelles and a cell wall composed of chitin
5. No mechanisms of locomotion
   6 most store their food as glycogen

Question 14

Features of plantae

Answer 14

1. They have chloroplast
2. They are autotrophs- they make their own food through photosynthesis
3. Their glucose storage molecule is starch
4. They are immobile although gametes of some plants moved using cilia or flagella
5. Their cell wall is made up of cellulose
6. They have a nucleus and other membrane bound organelles
7. They are multicellular

Question 15

Features of animalia

Answer 15

1. They are multicellular
2. They have no cell wall
3. They have a nucleus and other membrane bound organelles
4. They have 80S ribosomes
5. They are heterotrophs- they get their nutrients from eating other animals
6. Their glucose storage molecule is glycogen
7. They move with the aid of cilla, flagella or contractile proteins, sometimes in the form of muscular organs

Question 16

Why were there changes to the classification system?

Answer 16

Through the study of genetics and other biological molecules, scientists were able to study the evolutionary relationships between organisms

Question 17

Who and what was the new classification system?

Answer 17

Carl Worse proposed the new classification system which is known as the “3 Domain, 6 kingdom” system. It groups organisms using differences in the sequence of nucleotide in the cell’s ribosomal RNA

Question 18

What are the three domains?

Answer 18

Archaea, Bacteria and Eukarya

Question 19

Features of the Archaea domain

Answer 19

1. They have 70S ribosomes
2. Has circular DNA
3. Has several types of RNA polymerase

Question 20

Features of Bacteria Domain

Answer 20

1. Has 70S ribosomes
2. Have circular DNA
3. RNA polymerase contains 5 proteins

Question 21

Features of Eukarya domain

Answer 21

1. Has 80S ribosomes
2. Has linear DNA wrapped around histones
3. RNA polymerase has 12 proteins

Question 22

What are the 6 kingdoms using the Carl Woese classification system?

Answer 22

Plantae
Animalia
Fungi
Protoctista
Archaea bacteria
Eubacteria

Question 23

Why isn’t the “Prokaryotae” part of this system?

Answer 23

In this system, the prokaryotae kingdom becomes divided into two -Archaea bacteria and Eubacteria

Question 24

Explain why prokaryotes are now classified as two separate domains (3 marks)

Answer 24

This is due to the advancement in biological techniques which has enabled scientists to see differences in their chemical make-up with Eubacteria having peptidoglycan in their cell wall and Archaea bacteria don’t

Question 25

Describe how and why the classification systems have changed over time (6 marks)

Answer 25

Organisms were originally classified into two kingdoms based on major differences in characteristics (1) those that moved are animals and those that didn't are plants (1); scientific advances allowed smaller details to be observed (1); organisms divided into five kingdoms(1); plants, animals, fungi, protoctista, prokaryotes (1); Advances in science allowed DNA and proteins to be studied(1); provided evidence for evolutionary relationships (1); three domains system proposed by Carl Woese (1); relevant scientist mentioned (Linnaeus, Whittaker, Woese) (1)

Question 26

What is phylogeny?

Answer 26

It is the name given to the evolutionary relationships between organisms. It reveals which group a particular organism is related to, and how closely related these organisms are

Question 27

Features of a phylogeny tree

Answer 27

1. The oldest species are found at the base of the tree and the most recent species are found at the tips of the branches 2. The tips of the tree represent groups of descendent organisms(often species) 3. The nodes of the tree represent the common ancestor of those descendents. Two descendents split from the same nodes are called sister groups 4. The closer the branches of the tree are, the closer the evolutionary relationships between the species

Question 28

Advantages of phylogenetic classification

Answer 28

1. It is not based on grouping organisms 2. The taxonomic classification treated the same taxon as equivalent which is misleading