A3.1 Diversity of Organisms

Question 1

Define Organism

Answer 1

Any biological system that functions as an individual life form.

All organisms are composed of cells.

Question 2

Define Variation

Answer 2

Differences in any aspect of an organism. Can be discrete or continuous.

Question 3

Sources of genetic variation within a species

Answer 3

Reproduction (more often in sexual than asexual)

Question 4

Explain Discrete variation with examples

Answer 4

Traits that can be put into distinct qualitative categories.

Cause: usually influenced by one or a few genes. Can also be influenced by environment, not usually significantly.

E.g. Blood type, petal color, dominant hand.

can be shown using bar chart.

Question 5

Explain Continuous variation with examples

Answer 5

Traits that vary along a quantitative continuum. Most types of biological variation are continuous.

Cause: results from complex interactions between different genes, often with environment also impacting part of expression of phenotype.

E.g. Height, weight, root length of plants.

Question 6

Define Species according to the morphological species concept.

Answer 6

A species, according to the morphological species concept, is defined as a group of individuals that are classified together based on shared and distinctive morphological (structural) features. This concept identifies species primarily by observable physical characteristics such as body shape, size, and other anatomical traits.

Question 7

Define binomial nomenclature

Answer 7

A formal system used in biology to name species of living organisms.

Question 8

State the four rules of binomial nomenclature formatting

Answer 8

It is a two-part name: genus + species

Genus is capitalized, species is not

If typed, use italics.

If handwritten, underline.

Question 9

Outline why binomial naming system is used in science rather than local names.

Answer 9

Binomial nomenclature system known internationally, allowing for consistency in communication around world.

Question 10

Define species according to the biological species concept

Answer 10

A group of organisms that can interbreed and produce viable, fertile offspring but not with other groups.

Question 11

Describe limitations of the biological species concept

Answer 11

Hybrids.

Variation across geographical ranges.

Divergence during speciation.

Practical challenges of testing if reproduction is possible between groups.

Asexually reproducing organisms.

Question 12

Define Speciation

Answer 12

The formation of new and distinct species in the course of evolution.

Splitting pre-existing species is one way.

Question 13

Explain difficulties in distinguishing between populations of species during speciation

Answer 13

Genetically diverging populations can be hard to distinguish as unique species as the speciation is occurring because there is a continuum from merely somewhat restricted gene flow with the ancestral species and the complete reproductive isolation of the two resulting species.

Can be an arbitrary decision whether two populations regarded as same or different species.

Question 14

Chromosome number is a characteristic of each species

Answer 14

Large range.

does not necessarily mean more complex.

Could result in fusion or separation of chromosomes.

Question 15

Why is typical number of chromosomes in a diploid cell an even number

Answer 15

2 haploid cells. 2n= even.

Question 16

Number of chromosomes in humans and chimpanzees

Answer 16

48

Question 17

Evidence for hypothesis that chromosome 2 in humans arose from fusion of chromosome 12 and 13 with a shared primate ancestor.