Three Domains Of Life

Question 1

biodiversity

Answer 1

refers to all of the
variety of life that exists on Earth

Question 2

Taxonomy

Answer 2

-science of classifying

-Classification is an important step in understanding the present diversity and past evolutionary history of life on Earth

Question 3

Linnaean Classification

Answer 3

oAll modern classification systems have their roots in the Linnaean classification system. It was developed by Swedish botanist Carolus Linnaeus in the 1700s.
oIt consists of a hierarchy of groupings, called taxa.

Question 4

Unity in the diversity of life

Answer 4

A striking unity underlies the diversity of life; for example,
• Cell is the basic structural and functional unit of all organisms
• DNA is the universal genetic language common to all organisms
o near university of the genetic code provides evidence of the common ancestry of all life
• Unity is evident in many features of cell structure

Question 5

biological species

Answer 5

-is a group of populations whose members have the potential to interbreed in nature and produce viable, fertile offspring; they do not breed successfully with members of other such groups

-Gene flow between populations holds a species together genetically

-based on the potential interbreed not physical similarity

Question 6

Phylogeny

Answer 6

is the evolutionary history of a species or group of related
species

Question 7

Sister taxa

Answer 7

are groups that share an immediate common ancestor that is not shared by any other group

Question 8

phylogenetic tree

Answer 8

-represents a hypothesis about evolutionary relationships
- Each branch point represents the divergence of two evolutionary lineages from a common ancestor

Question 9

An organism’s evolutionary history is documented in its genome

Answer 9

▪ Comparing nucleic acids (DNA/RNA) or other molecules to infer relatedness is a valuable approach for tracing organisms’ evolutionary history
▪ DNA that codes for rRNA changes relatively slowly and is useful for investigating branching points that diverged hundreds of millions of years ago
▪ Examination of the sequences of the ribosomal ribonucleic acid (rRNA) (the 16s RNA) from different organisms and other characteristics concluded they comprised three phylogenetic domains

Question 10

3 domains of life

Answer 10

Bacteria(prokaryotes)
Archaea (prokaryotes)
Eukarya

Answer 11

• Prokaryotes were the first organisms to inhabit the Earth
• Prokaryotes thrive almost everywhere, including places too acidic, salty, cold, or hot for most other organisms

-Most are unicellular, although some species form colonies
-Most prokaryotic cells are 0.5–5 μm, much smaller than the 10–100 μm of many
eukaryotic cells
-Prokaryotic cells have a variety of shapes
-The three most common shapes are spheres (cocci), rods (bacilli), and spirals

Question 12

Bacteria

Answer 12

Most bacterial cell walls contain peptidoglycan, a network of sugar polymers cross-linked by polypeptides

Question 13

Archaea

Answer 13

• Archaea share certain traits with bacteria and other traits with eukaryotes
• Archaea contain polysaccharides and proteins but lack peptidoglycan
• Some archaea live in extreme environments and are called extremophiles
o Extreme halophiles live in highly saline environments o Extreme thermophiles thrive in very hot environments

Question 14

Domain Eukarya

Answer 14

• includestheprotistsandthreekingdoms
o Plants, which produce their own food by photosynthesis o Fungi, which absorb nutrients
o Animals, which ingest their food

Question 15

Protists

Answer 15

• Exhibit more structural and functional diversity than any other group of eukaryotes
• Thesearemostlysingle-celledorganisms
• Some protists are less closely related to other protists than they are
to plants, animals, or fungi
• Some protists reproduce asexually, while others reproduce sexually, or by the sexual processes of meiosis and fertilization

Question 16

Genome Size

Answer 16

• Genomes of most bacteria and archaea range from 1 to 6 million base pairs (Mb)
• Genomes of archaea are mostly within this size range
• Eukaryotic genomes tend to be larger
• Most plants and animals have genomes greater than 100 Mb; humans have 3,000 Mb
• Within each domain there is no systematic relationship between genome size and phenotype

Question 17

Number of Genes

Answer 17

• Free-living bacteria and archaea have 1,500 to 7,500 genes
• Unicellular fungi have about 5,000 genes and multicellular eukaryotes up to at least 40,000 genes
• Number of genes is not correlated to genome size

Question 18

Eukarya: animals

Answer 18

▪ Most animals are composed of cells organized into tissues that have different functions
▪ Tissues make up organs, which together make up organ systems
▪ Some organs, such as the pancreas, belong to more than one organ system

Question 19

There are four main types of animal tissues:

Answer 19

▪ Epithelial
▪ Connective
▪ Muscle
▪ Nervous

Question 20

Epithelial tissue

Answer 20

▪ It covers the outside of the body and lines the organs and cavities within the body
▪ It contains cells that are closely joined
▪ The shape of epithelial cells may be cuboidal, columnar, or squamous
▪ The arrangement of epithelial cells may be simple (single cell layer), stratified (multiple tiers of cells), or pseudostratified (a single layer of cells of varying length)

Eg; cuboidal epithelium,simple columnar epithelium,simple squamous epithelium,pseudostratifided columnar epithelium

Question 21

Connective tissue

Answer 21

Blood
Cartilage
Adipose tissue
Bone
Collagenous fiber

Question 22

Connective Tissue

Answer 22

▪ Connective tissue mainly binds and supports other tissues
▪ There are three types of connective tissue fibre, all made of protein:
oCollagenous fibres provide strength and flexibility oReticular fibres join connective tissue to adjacent tissues oElastic fibres stretch and snap back to their original length
▪ Connective tissue contains cells, including
oFibroblasts, which secrete the protein of extracellular fibers oMacrophages, which are involved in the immune system

Question 23

6 types of connective tissue

Answer 23

o Loose connective tissue binds epithelia to underlying tissues and holds organs in place
o Fibrous connective tissue is found in tendons, which attach muscles to bones, and ligaments, which connect bones at joints
o Bone is mineralized and forms the skeleton
o Adipose tissue stores fat for insulation and fuel
o Blood is composed of blood cells and cell fragments in blood plasma o Cartilage is a strong and flexible support material

Question 24

3 types Muscle tissue

Answer 24

Cardiac
Skeletal
Smooth

Question 25

Muscle tissue

Answer 25

▪ Muscle tissue is responsible for nearly all types of body movement ▪ Muscle cells consist of filaments of the proteins actin and myosin,
which together enable muscles to contract
▪ Muscle tissue in the vertebrate body is divided into three types:
o Skeletal muscle, or striated muscle, is responsible for voluntary movement
o Smooth muscle is responsible for involuntary body activities o Cardiac muscle is responsible for contraction of the heart

Question 26

Nervous tissue

Answer 26

-Nervous tissue is the groups of organized cells in the nervous system
—Nervous tissue is grouped into two main categories:
- Neurons,ornerves,transmit electrical impulses
-Glia,orneuroglia,formmyelin,supportandprotectneurons.

Question 27

Bacteria

Answer 27

▪ Most bacterial cell walls contain peptidoglycan, a network of sugar polymers cross-linked by polypeptides