A3.1 Diversity of organisms Flashcards
(33 cards)
What is variation?
Differences in any aspect of organisms
List some aspects of an organism that can vary.
- Visual appearance, such as fur colour or body length
- Behaviour, such as mating rituals and level of aggression
- Biochemistry, such as antibiotic resistance or metabolic products
How is genetic variation generated?
- Mutation occurs
- Alleles are combined in different ways during sexual reproduction
Give examples of environmental factors that may generate variation.
- Environmental temperatures
- Nutrient availability
- Oxygen concentration
Nomenclature
Genus, Species
What is the binomial naming system?
name species according to their taxa,
What is the biological species concept?
A group of organisms that can interbreed to produce fertile offspring
Name a limitation of the biological species concept.
- Asexual reproduction
- Fertile hybrids
- Extinction
What is speciation?
The process by which one species gives rise to two or more new species
Because of
* divergence
* geographical/temporal/behavuoral isolation
* reproductive isolation
* selective pressures
What is a diploid cell?
A cell that contains two complete sets of chromosomes (2n)
What are haploid cells?
Cells that contain one complete set of chromosomes (n), usually gametes
What happens during fertilization?
The nuclei of haploid gametes fuse together to form the nucleus of a diploid zygote
How many chromosomes do humans have in a diploid cell?
46
What is a karyotype?
The appearance of a complete set of an individual’s chromosomes, including their number, size, shape, and banding
What is a karyogram?
An image that shows all of the chromosomes in a cell, arranged by size, shape, and banding pattern
How is a karyogram produced?
- Cells are stained and viewed under a light microscope
- Photographs are taken during metaphase of cell division
- Photographs are cut up and arranged by size, shape, and banding pattern
What is the significance of chromosome number in species classification?
Differences in chromosome number is one reason why organisms from different species are unable to breed together successfully
How many chromosomes do chimpanzees have?
48 chromosomes
What is one possible mechanism for the loss of chromosomes during human evolution?
A pair of chromosomes fused with another pair to form a single pair
What hypothesis did scientists test regarding human chromosome 2?
Chromosomes in pairs 12 and 13 in a common ancestor fused to form the chromosomes in human pair 2
What evidence supports the chromosome fusion hypothesis?
- Chimpanzee chromosomes 12 and 13 match the length of human chromosome 2
- Centromere location of chimpanzee chromosome 12 matches that of human chromosome 2
- Satellite DNA on human chromosome 2 corresponds to chimpanzee chromosome 13
- Banding patterns of chimpanzee chromosomes correspond to human chromosome 2
- Human chromosome 2 contains telomeric DNA in the middle
What evidence does not support the chromosome fusion hypothesis?
- Length of chimpanzee chromosomes 12 and 13 combined is not a perfect match for human chromosome 2
- Centromere location of chimpanzee chromosome 13 does not match that of human chromosome 2
What defines a testable hypothesis?
It must have evidence that supports or refutes it
genome?
All of the genetic information in an organism
