A3.1 diversity of organisms

Question 1

basis of variation between organisms

Answer 1

-no two individual organisms share the same traits
-patterns of variation are complex and are the basis for naming and categorizing objects

Question 2

morphological species definition

Answer 2

individuals that belong to the same species have external physical similarities

Question 3

biological species definition

Answer 3

population whose members can interbreed and produce fertile offspring to be considered same species

Question 4

what is gene flow

Answer 4

how genes go from on individual/ population to another

Question 5

categories of taxa (humans)

Answer 5

DOMAIN
KINGDOM (anamalia)
PHYLUM(chordata)
CLASS (mammalia)
ORDER (primate)
FAMILY (hominidae)
GENUS(homo)
SPECIES(sapiens)

Question 6

discontinuous
continuous

Answer 6

discontinuous= when variation can be placed into distinct categories
continuous=when variation has a wide range of possibilities

Question 7

original morphological concept

Answer 7

-scientists in 18th centaury had difficulty in identifying plants
Linnaeus idea: to categorize all living organisms, giving them a name using a uniform system
-creating names in latin/greek

-based classification system and names on physical appearance= morphological classification

Question 8

the binomial systems for naming organisms

Answer 8

-scientific name based on species
-‘‘two-names’’
-nomenclature= system used for naming

first word is GENUS (capital)
second word if species (lower)

-organisms in the same genus will more similar characteristics compared to organisms in another genus

Question 9

three main rules when using binomial nomenclature

Answer 9

1- each organism has its own name
2- names can be universally understood
3-some stability in system- no one can change without valid reason

Question 10

biological species concept

Answer 10

(another definition of a species proposed in 1942)
-in order to be classified as the same species, individuals must be able to breed together to produce fertile offspring

Question 11

what the biological species concept doesn’t show

Question 12

speciation

Answer 12

process of splitting one species into two or more groups that can no longer reproduce

-very gradual process, rather than a single act, the traits become more different and results in two new species that have a common ancestor

Question 13

diploid cells

Answer 13

A diploid cell is a cell that contains two complete sets of chromosomes
-most human body cells
-have even chromosome number
2n

Question 14

haploid cells

Answer 14

A haploid cell has only a single set of chromosomes.
-gamet cells
-n

Question 15

chromosome number in humans and chimpanzees

Answer 15

humans= 46 (23n x 2)
chimps=48 (24 x 2)

Question 16

what is a karyogram

Answer 16

representation of the chromosomes found in a cell arranged according to standard format- size/shape

Question 17

what is a karyotype

Answer 17

specific number and appearance of chromosomes in an organisms cell, represented by a karyogram

Question 18

what does the shape of a chromosome depend on

Answer 18

THE CENTROMERE= which is a structure that holds the two chromatids together

Question 19

steps on how karyogam image is obtained

Answer 19

1) cells are stained- prepared on glass slide under light microscope
2)photomicrograph image is obtained during specific parts of cell division
3) image cut, separated
4) image ordered in size and position of centromere

Question 20

question of human chromosome 2, and its hypothesis

Answer 20

-apes have 48 chromosomes and since we have a common ancestor, what happened with out chromosome number?

2 Hypothesis;
1- complete chromosome disappeared
2- two chromosomes from earlier common ancestor fused together to become a single chromosome

(first hypothesis is unlikely)

Question 21

characteristics that help identify chromosome

Answer 21

-2 characteristics that help identify chromosome; shape + bonding patterns

‘x’ shape= METACENTRIC
centromere at one end= ACROCENTRIC

Question 22

evidence for fusion and formation of human chromosome 2

Answer 22

hypothesis= chromosome 2 arose from fusion of chromosomes 12 and 13 in a shared ancestor
EVIDENCE:
-non human acrocentric chromosomes 12, 13 had similar length to human chromosome 2
-centromere positions lined up in chromosome 12
-long arm of chimp chromosome 12 matches short arm of human chromosome 2
-long arm of chimp chromosome 13 matches the long arm of human chromosome 2
-presence of telomeric DNA , that is not supposed to be at center of chromosome, but rather only at tips. Implies fusion

Question 23

reason for diversity in a species

Answer 23

-humans share the same genes, but not the same version of each gene
-differences are found in DNA sequences of base pairs; small portion of people may have a G rather then T in a base pair
-these variation start out as mutations
this is called SINGLE NUCLEOTIDE POLYMORHISM

Question 24

what is single nucleotide polymorphism

Answer 24

-variation involving one base
-100-300 bases in human genetic code has a SNP, very small percent are functional, meaning them show in a persons phenotype.

Question 25

human genome project
techniques used

Answer 25

-international 13 year effort to sequence the complete human genome and order all bases in human DNA

-PCR to prepare samples
-computers
-florescent labelling
-lasers

Question 26

why genomes vary in size

Answer 26

determined by the total amount of DNA (100 genes, 10,000 genes)
means that some eukaryotes will posses things others don’t

Question 27

2 ways that can be used when comparing genetic differences

Answer 27

-can use DNA code
-amino acid sequence (can be looked up in database and corresponds to 20 possible amino acids)

Question 28

what are phylogenetics

Answer 28

techniques to see how organisms are related to eachother

Question 29

future uses for whole genome sequencing

Answer 29

-reduction of cost
-speeding of sequences
-global market growth
-personalized medication
-production of new medicine

Question 30

limitations to biological concept of species

Answer 30

1- insufficient information- for fossils, reproduction cant be observed, so phylogenetic concept is used
2- uniparental reproduction- asexually reproducing species do not interbreed (self-fertilization, parthegenesis, pseydogamy, vegatative reproduction)
3-evolutionary intermediacy, species have intermediate phases, cant say species belong to the same with missing information
4- some organisms have mosaic DNA, due to multiple horizontal gene transfer in their life
5- some hybrids can reproduce

Question 31

horizontal gene transfer

Answer 31

= transferring gene vertically from one species to another’-bacteria exchange genetic material throughout their life, and means they have mosaic of genes

Question 32

interspecific hybrids

Answer 32

-the mating of two different species to form a usually infertile offspring

-impacts development
-has an atypical chromosome number and makes homologs pairs difficult to match during meiosis
-reduces fertility

Question 33

hybrid zone

Answer 33

region in which members of different species meet and mate producing some organisms of mixed ancestry

Question 34

what is a dichotomous key

Answer 34

-way to identify newly encountered organisms
-helps figures out what taxa they belong to
- yes or no questions
-keeps going until you have a name

Question 35

identifying species using barcode

Answer 35

barcode identification number matched against database of sequences that are known to belong to previously identified organisms

DNA barcode= short DNA sequence inside organisms cell that can be used for identification

Question 36

what is environmental DNA
+ strengths and weaknesses

Answer 36

-DNA extracted from environment rather than organisms, like water, soil and can identify species present in an ecosystem

+ no capturing, single sample, time efficient, sees habitat health

• only gives indication of presence, not size
  no indication for dead or living
  chemical incompatibilities, like soil interference