Theme A: A3 Unity and Diversity Organisms - A3.1 Diversity Organisms

Question 1

ways of classifying organisms

Answer 1

generally classified based on morphology, but also:

1) feeding habits: carnivore/ herbivore/ makes its own food
2) habitat: land-dwelling/ aquatic
3) movement: sessile/ free moving
4) daily activity: nocturnal/ diurnal
5) risk: harmless/ venemous
6) anatomy: plant/ animal/ vertebrate/ invertebrate

Question 2

morphology

Answer 2

physical appearance of an organism

Question 3

taxon (plr. taxon)

Answer 3

each category an organism is placed into

Question 4

8 levels of taxonomy (largest to smallest)

Answer 4

the largest is domain, followed by:
1) kingdom
2) phylum
3) class
4) order
5) family
6) genus
7) species

Question 5

discontinuous

Answer 5

when variation can be placed into distinct categories (e.g. type A blood and type B blood)

Question 6

continuous

Answer 6

when variation has a wide range of possibilities (height of a tree)

Question 7

binomial nomenclature

Answer 7

first name is capitalised and refers to the genus (Homo)

second name is lowercase and refer to the species (sapiens)

Question 8

3 main objectives of binomial nomenclature

Answer 8

1) each organism has a unique name that can’t be confused with another organism
2) names can be universally understood
3) the system is stable so people can’t change names of organisms without valid reasons

Question 9

biological species concept

Answer 9

this definition suggests that in order to be classified the same species individuals must be able to breed together and produce fertile offspring.

Question 10

speciation

Answer 10

process by which a population is separated into 2 groups that can no longer reproduce together. Overtime, one part evolves in a different way to the other. Gradually the result is two new species with a common ancestor.

Question 11

diploid

Answer 11

diploid cells have two complete sets of chromosomes, one set from each parent. In humans, this number is 46. Body cells are diploid.

remember: diploid = 2n

Question 12

gametes

Answer 12

a reproductive/sex cell.

Question 13

haploid

Answer 13

Haploid cells are those that have only a single set of chromosomes. In humans, this number is 23. Gametes (sperm and egg cells) are haploid.

remember: haploid = n

Question 14

karyogram

Answer 14

representation of chromosomes found in a cell arranged according to a standard format. the chromosomes are placed according to their size and shape.

Question 15

karyotype

Answer 15

specific number and appearance of the chromosomes in the indidividual’s cells.

Question 16

centromere

Answer 16

The part of a chromosome that holds two sister chromatids (copies of the chromosome) together. A chromosomes shape mainly depends on the position of its centromere.

Question 17

2 characteristics that help identify a chromosome

Answer 17

1) shape (position of centromere)
2) banding pattern

Question 18

acrocentric shape

Answer 18

centromere at one end, one arm pf the chromosome is much shorter and the other other much larger.

Question 19

metacentric shape

Answer 19

chromosomes in the shape of an X that have a centromere close to the centre.

Question 20

telemeres

Answer 20

caps at the tips of chromosomes that contain repeating sequences of DNA (telemetric DNA) and provide protection.

Question 21

single nucleotide polymorphism (SNP)

Answer 21

a variation involving 1 base pair in a sequence of DNA. around every 100-300 bases n a humans genetic code contains an SNP. most SNPs are neutral and won’t affect one’s phenotype, where around 5% are functional. this DNA variation can lead to genetic disease or increased susceptibility to diseases.

Question 22

phenotype

Answer 22

a physical expression of a gene, like blood type or colour vision

Question 23

phylogenetics

Answer 23

the study of evolutionary relationships among organisms. Using whole genome sequencing, scientists compare entire DNA sequences to analyse genetic similarities and differences, which helps construct phylogenetic trees. These trees show common ancestry and the evolutionary divergence of species based on their complete genomes.

Question 24

personalised medicine

Answer 24

information about a person’s genetic makeup that can be applied to an individual when prescribing treatments

Question 25

parthogenosis

Answer 25

insects usually reproduce by having males fertilise the eggs of females. However, the females of certain insects can often produce young without mating a male. this involves development of a female (rarely a male) gamete (sex cell) without fertilization.

Question 26

vegetative propagation

Answer 26

a natural form of asexual reproduction in plants. for example, farmers can plant last year’s potatoes in their fields to grow new potato plants

Question 27

binary fission

Answer 27

the asexual reproduction of bacteria. during the process, bacterial cells grow larger, copy their genetic material, and split into two daughter cells that are identical to the original parent cell.

Question 28

vertical gene transfer

Answer 28

generations passing DOWN their genes to the next generation

Question 29

horizontal gene transfer

Answer 29

usually organisms only receive genetic material once in their life during reproduction from the fusion of male and female sex cells, but bacteria - for example - can exchange genetic material within their lifetime through plasmid transfer.

Question 30

the tree of life concept

Answer 30

all members of a species have a common lineage and come from a series of common ancestors.

Question 31

xenologs (jumping genes)

Answer 31

Xenologs are genes that are transferred between organisms via horizontal gene transfer (HGT), rather than inherited from a common ancestor. This process allows genes to “jump” between species. These genes can integrate into the host genome, potentially introducing new functions or traits.

e.g. these genes travel in plasmids from one bacterium to another.

Question 32

interspecific hybrid

Answer 32

bred by mating individuals from 2 different species, through normally from within the same genus. the offspring display traits and characteristics of both parents, but are often infertile due to an uneven number of chromosomes that makes it difficult for homologous pairs to match up during meiosis. (e.g. mules from female horse and male donkey)

Question 33

DNA barcode

Answer 33

short sequence of DNA composed of several hundred base pairs inside an organism’s cell that can be used to quickly identify the species. mitochondrial DNA is used to identify animals; ribosomal RNA is used for the barcodes of prokaryotes.

Question 34

environmental DNA (eDNA)

Answer 34

DNA collected from the environment rather than an organisms.

Question 35

bioindicators (indicator species)

Answer 35

these organisms are so sensitive to certain types of pollution that their presence in an ecosystem indicates a lack of pollution. conversely, their sudden disappearance suggests the appearance of a source of pollution.

Question 36

genome sizes

Answer 36

The genome is all the genetic information of an organism.
It is measured by the total amount of DNA, measured by the number of base pairs.