A3.1 diversity of organisms (1) Flashcards
Define an organism.
a living thing that functions as an individual
Define variation.
the differences in traits or characteristics among individuals within the same species.
List sources of genetic variation within a species.
Mutation.
random mating between organisms.
random fertilization.
crossing over (or recombination) between chromatids of homologous chromosomes during meiosis.
Define species according to the morphological species concept.
groups of individuals which are morphologically similar (similar traits) to each other, and morphologically different from other species.
Define binomial nomenclature.
a system used to name living organisms with two parts: the genus name and the species name.
Outline why the binomial naming system is used in science rather than local names.
- Allows organisms to be named according to globally recognized scheme.
- Allows for identification and comparison of organisms based on recognized characteristics.
- It can show how closely related organisms are, allowing for the prediction of evolutionary links.
- It makes it easier to collect, sort and group information.
Define species according to the biological species concept.
a species is defined as a group of organisms that can interbreed and produce fertile offspring
Describe limitations of the biological species concept, with explanation of hybrids and geographical separation.
Hybrids: Different species can sometimes mate and produce offspring, called hybrids (like ligers from lions and tigers). This shows that species boundaries aren’t always clear since hybrids can be fertile.
Geographical separation: When populations are separated by distance (like mountains or rivers), they may evolve into different species. If they meet again, they might still be able to breed, complicating their classification as separate species.
Asexual reproduction: This concept mainly applies to organisms that reproduce sexually. Asexual organisms, like bacteria, don’t fit well into this definition since they don’t mate.
Horizontal Gene Transfer: Transfer of genes between unrelated species is common amongst bacteria.
Define speciation.
the splitting of one species into two or more species.
Explain why the typical number of chromosomes in a diploid cell is an even number.
Diploid eukaryotic cells will have two complete sets of chromosomes in their nucleus, resulting in an even number of chromosomes in each cell.
State the number of chromosomes in humans and in chimpanzees.
46
Evaluate the evidence for the hypothesis that chromosome 2 in humans arose from the fusion of chromosomes 12 and 13 with a shared primate ancestor
**Matching patterns: **The two chimpanzee chromosomes (12 and 13) have patterns that look a lot like parts of human chromosome 2.
Join point: There’s a spot on human chromosome 2 where it looks like two chromosomes fused together, and it has special DNA usually found at the ends of chromosomes.
Size match: If you combine the size of the two chimpanzee chromosomes, they’re a*bout the same length as human chromosome 2.
Outline the cause and effect of “single-nucleotide polymorphisms” in genomes.
Cause: mutations, copying errors, genetic drift, natural selection
Effects: trait variation, disease risk, drug response, genetic markers
Describe reasons why a larger genome does not necessarily indicate presence of more genes.
Non-Coding DNA: Much of the genome doesn’t code for proteins but helps regulate genes and maintain stability.
**Gene Size: **Genes vary in size, and the number of genes depends on how coding regions are arranged, not the total DNA.
Gene Duplication: Genes can be copied, forming a family of similar genes but still functioning as one.
Compare sexual and asexual reproduction.
asexual reproduction needs only one organism in order to reproduce more offspring that are identical to each other and the parent. Sexual reproduction involves a male and female cell combining to form offspring that are genetically unique to each other’s parents.
