IB DP Biology HL A3.1 Diversity of organisms Flashcards

[q] Explain variation

[a] -No 2 individuals are identical.
-Patterns of variation between organisms are complex.
-Patterns used to name organisms.

[q] What is the binomial system for naming organisms?

[a] Genus species
-1st letter of genus name must be capitalized.
-1st letter of species name is lowercase.
ex: Homo sapiens.
-Species in a genus have similar traits
ex: Big cats.
-Name organisms so that we can track them through a period of time.

[q] What is the biological species concept?

[a] Species: a group of organisms that can breed & produce fertile offspring.
-Problems:
1. Only works for species that are sexually reproducing.
2. Some species can form hybrids.
-Phylogenetic species: smallest set of organisms that share a common ancestor.
-Recognition species concept: species that recognize each other as mates.

[q] What are the difficulties distinguishing species & populations?

[a] -Are they genetically different enough to be separate species?
-Arbitrary distinctions – hard to distinguish species.
-Can they reproduce if brought back together?
arbitrary: left up to choice; people decide

[q] Do species share traits?

[a] Originally, definition of a species was sharing morphology.
-Species still share the same traits since they’re from a common ancestor, but sometimes organisms that look very similar are actually separate species.
-They share traits, but sometimes genetics don’t match.
-ex: chimpanzees & bonobos.

[q] Explain the diversity of chromosome #s of plant & animal species
*chromosome: long strands of DNA

[a] –Different species have different chromosome #s.
-Humans have 46, chimpanzees have 48.
-Diploid cells always have an even # (always paired: 1 from sperm, 1 from egg).
*Chromosomes can be broken and put back together.
*Diploid: cells that have 2 copies of chromosomes, except games (haploids), in which each cell carries only 1 copy of each chromosome.

[q] Explain how chromosome # is a shared trait within a species

[a] -Each species have the same # of chromosomes.
-The likelihood of infertile offspring is much more higher if they have different #s of chromosomes.
ex: horses – 64, donkey – 62, mule – 63.
*uneven # of chromosomes causes sex cells to not function properly = infertile.

[q] What are karyograms & karyotypes?

[a] -Karyogram: the images of the whole set of chromosomes.
-Karyotype: the banding pattern, length of chromosome.
-Look at karyogram to get karyotype.

[q] How do you get evidence for fusion of chromosome 2 in humans?
*fusion: male & female gamete merge together to form a new organism

[a] -Use karyotype & line them up.
-Compare sequences & banding patterns.
-Chimps, gorillas, and orangutans all have 2 instead of 1.

[q] Identify DNA

[a] -Genes can be turned on & off.
-Humans & humans: 99.9%.
-Humans & chimps: 98.9%.

[q] Explain genome

[a] All the genetic information of an organism.
-Organisms of the same species have almost the exact same DNA.
-Changes are caused by single – nucleotide polymorphisms.
-Single base changes.

[q] Explain diversity of genome size

[a] -Genome vary greatly in length of DNA between species.
-There is very little difference in a species in terms of length of DNA.
-Genomes are stored in databases for easy access.

[q] Explain genome sequencing

[a] -Moore’s law: speed of computing power increases exponentially.
-In 2004, Next Generation Sequencing (NGS) became a lot cheaper & easier to do.
-Produced more data & papers.
– Can be used to identify immunity, diseases & genomes.

[q] How does bacteria reproduce?

[a] -Asexually
-Other organisms that can asexualize: plants, birds, fungi, chicken, certain reptiles (lizards).

[q] What are the problems w/ the biological species definiton?

[a] -Most single celled organisms, some plants, some fungi, & some animals reproduce asexually – which means you cannot apply the biological species definition towards groups of organisms that can interbreed.
-Bacteria can also transfer genes to other bacteria through horizontal gene transfer – this is how antibiotic resistance can spread easily through a population & natural selection.
*If bacteria passes genes to other bacteria through horizontal gene transfer, then they all become resistant to the antibiotic.

[q] What is the dichotomous keys? Di – 2; chitomous – parts

[a] -Use morphology to quickly identify organisms using a dichotomous keys.
-If yes then…, if no then…
-2 parts to each questions: yes or no
-Used to identify species quickly since there’s millions of species.

[q] What’s the purpose of DNA barcoding?

[a] -Species can be identified using DNA barcodes (short sections of DNA).
1. Collect DNA from environment.
2. Sequence it & compare to known sequences.

[q] List the 3 different species concept

[a] 1. Biological species concept: group of organisms that can successfully breed & produce fertile offspring.
2. Phylogenetic species concept: smallest set of organisms that share a common ancestor & all posess a combination of certain defining or derived traits.
3. Recognition species concept: organisms that can recognize each other as potential mates.

[q] Define organism

[a] Any biological system that functions as an individual life form. All organisms are composed of cells.

[q] Define variation

[a] Feature of life. Refers to differences between members of a group. Can be discrete or continuous.

[q] List sources of genetic variation within a species

[a] Mutation, Genetic Recombination, Gene Flow, Sexual Reproduction, Genetic Drift, Adaptive (Natural) Selection, Artificial Selection, Epigenetic Changes.

[q] Compare discrete and continuous variation

[a] –Discrete–
Desc: traits that can be put into distinct qualitative categories.
Cause: usually influenced by only one or a few genes. They can also be influenced by environment, although usually not significantly.
Examples: hand used for writing, blood type.
–Continuous–
Desc: traits that vary along a quantitative continuum. Most types of biological variation are continuous.
Cause: result from complex interaction between many different genes (“polygenic”), often with the environment playing a significant part in the expression of the phenotype.

[q] Compare variation within and between species

[a] –Within–
Definition: Variation within a species, often referred to as infraspecific variation, encompasses the genetic and phenotypic diversity found among individuals within a single species.
Causes: It is primarily driven by factors such as mutations, recombination, gene flow, sexual reproduction, genetic drift, and natural selection acting on the gene pool of a species.
Range: The range of variation within a species can be extensive. It includes differences in traits such as color, size, behavior, and physiology.
Importance: This level of variation is crucial for the species’ adaptation and evolution. It allows a species to respond to changing environmental conditions and ensures its long-term survival.
–Between–
Definition: Variation between species, also known as interspecific variation, pertains to the differences and diversity observed when comparing different species within the same taxonomic group.
Causes: These differences are a result of accumulated changes over evolutionary time. They can include variations in anatomy, physiology, genetics, behavior, and ecological niches.
Range: The range of variation between species can be significant, leading to diverse forms of life, from microscopic bacteria to large mammals, each adapted to specific environments and ecological niches.
Importance: Interspecific variation is the basis of biological diversity and is crucial for the functioning of ecosystems. It is a product of the evolutionary process and contributes to the stability and resilience of ecosystems by creating a web of interdependencies.

[q] Define Population

[a] a group of organisms of the same species in the same area. Even though they are the same species, the individual organisms of the population vary from each other.

[q] Define Community

[a] Communities are the populations of two or more different species occupying the same geographical area at the same time. There is great variation between different species.

[q] Define species according to the morphological species concept.

[a] the morphological species concept defines a species primarily based on physical appearances and characteristics, making it a practical approach for many biological disciplines, especially when genetic information is not readily obtainable.

[q] Define binomial nomenclature.

[a] Classification system in which each species is assigned a two-part scientific name.

[q] State four rules of binomial nomenclature formating.

[a] 1. the genus name beings with a capital letter.
2. the species name begins with a lowercase letter.
3. in print, the name is in italics (underline if handwritten).
4. after one use in a text, Genus name can be abbreviated to the first letter.

[q] Outline why the binomial naming system is used in science rather than local names.

[a] Reflects evolutionary relationships between organisms. All members of the same genus will share a common ancestor. Just from the name it is known that the the Pan paniscus and Pan troglodytes are more closely related to each other than either is to the Gorilla gorilla.
Enables scientists to talk to each other in the same language. The same species can have many different local names so binomial nomenclature allows for consistency in communication around the world.

[q] Define species according to the biological species concept.

[a] Reproductive Isolation: According to this concept, members of the same species can potentially interbreed with each other, while they are reproductively isolated from individuals of other species. Reproductive isolation mechanisms can be prezygotic (prevent mating or fertilization) or postzygotic (act after fertilization, reducing the fitness of hybrids).
Genetic Compatibility: Members of the same species are expected to share a high degree of genetic compatibility, which allows them to produce viable and fertile offspring when they mate. When populations are reproductively isolated from each other, genetic differences accumulate over time, leading to speciation.
Emphasis on Natural Populations: The biological species concept is primarily applied to naturally occurring populations. It may not be as applicable to asexual or clonal organisms, fossils, or species with very limited geographic ranges.

[q] Describe the limitations of the biological species concept, with mention of hybrids and geographical separation.

[a] Hybridization: It doesn’t account for hybridization between species, where different species can produce viable and fertile offspring. In such cases, it can be challenging to define species boundaries solely based on reproductive isolation.
Geographical Separation: It doesn’t apply well to species that are geographically isolated and unable to interbreed due to physical barriers. It may lead to difficulties in classifying such isolated populations as separate species.
These limitations highlight situations where the biological species concept may not provide clear distinctions between species.

[q] Define speciation

[a] the formation of new and distinct species in the course of evolution.

[q] Explain the difficulties in distinguishing between populations and species during speciation. ​

[a] Gradual Change: The process of speciation often occurs gradually, with small changes accumulating over time. There is no clear point where one population becomes a distinct species, making it hard to pinpoint when speciation has occurred.
Intermediates: During speciation, there can be intermediate populations that share characteristics of both the original and the emerging species. This blurs the lines between what is considered a separate species.
Hybridization: Hybridization between populations or species can occur, creating fertile offspring that share genetic material from both parent groups. This makes it difficult to classify these hybrid populations as either one species or another.
Geographic Isolation: If populations are geographically isolated, it can be challenging to assess their genetic compatibility and potential for interbreeding, especially if they are not in direct contact.
Lack of Clear Criteria: There is no universally agreed-upon set of criteria that definitively define when one population has become a new species. Different species concepts (e.g., biological, morphological, ecological) may yield different results in different scenarios.
These difficulties illustrate the complexity of the speciation process and the challenge of distinguishing populations and species, especially when considering the various factors that come into play during evolution.

[q] Explain why the typical number of chromosomes in a diploid cell is an even number.

[a] The typical number of chromosomes in a diploid cell is an even number because chromosomes in a diploid cell are usually organized into pairs. Each pair consists of one chromosome from the mother and one from the father. This pairing, or homologous pairing, ensures that the genetic material is distributed evenly during cell division. Having an even number of chromosomes allows for a more balanced and accurate distribution of genetic information, which is crucial for the proper functioning and development of an organism.

[q] Define karyotype and karyogram.

[a] Karyotype: A karyotype is a visual arrangement or display of an individual’s chromosomes, typically organized by size, shape, and banding patterns. It provides a snapshot of an organism’s complete set of chromosomes, showing their number and structural characteristics.
Karyogram: A karyogram is a specific, standardized image or photograph of a karyotype, with chromosomes arranged in a systematic order for detailed examination. It is a visual representation of an individual’s chromosome set that allows for the analysis of genetic information and identification of chromosomal abnormalities.

[q] List the characteristics by which chromosomes are paired and arranged on the karyogram.

[a] Size: Chromosomes are typically arranged in order of size, from the largest to the smallest.
Shape: The shape of chromosomes, which can vary from metacentric (V-shaped) to telocentric (rod-shaped), is considered when arranging them.
Band Patterns: Chromosomes are often grouped based on their banding patterns, which are created by staining techniques, revealing unique patterns of dark and light bands on the chromosomes.
Centromere Position: The position of the centromere, which divides chromosomes into short and long arms, is used to further distinguish and arrange them.
These characteristics help create a standardized and organized representation of an individual’s chromosome set for analysis and diagnosis.

[q] Define autosome and sex chromosome.

[a] Autosome: any chromosome that is not a sex chromosome
Sex chromosome: type of chromosome responsible for the chromosomal determination of the sex of an individual

[q] Deduce the sex of a human individual given a karyogram.

[a] If the karyogram shows two X chromosomes (XX), the individual is female.
If the karyogram shows one X and one Y chromosome (XY), the individual is male.

[q] Define genome, gene and allele.

[a] Genome: A genome is the complete set of an organism’s genetic material, including all of its genes, DNA sequences, and genetic information. It contains the instructions necessary for the development, functioning, and reproduction of the organism.
Gene: A gene is a specific segment of DNA that carries the instructions for building a particular protein or performing a specific function in an organism. Genes are the basic units of heredity and play a crucial role in determining an organism’s traits.
Allele: An allele is a variant or alternative form of a gene that occupies a specific position (locus) on a chromosome. Alleles can differ from one another in terms of the DNA sequence they carry, and they can result in variations in traits among individuals of a species. Alleles may be dominant or recessive, influencing the expression of a particular trait.

[q] Outline the cause and effect of “single-nucleotide polymorphisms” in genomes.

[a] –Cause–
Mutations: Random changes in DNA sequences that can occur during DNA replication, environmental exposure, or other factors. Mutations can lead to the creation of new SNPs.
Genetic Diversity: Over time, populations accumulate genetic diversity through mutations and genetic recombination. Some of these variations become common SNPs within a population.
–Effect–
Trait Variation: SNPs can contribute to individual differences in physical traits, such as eye color, hair color, and height. They can also affect susceptibility to specific genetic diseases.
Pharmacogenetics: SNPs can influence an individual’s response to drugs. Variations in drug metabolism-related SNPs can impact how effective a medication is or whether it may cause adverse reactions.
Disease Susceptibility: Certain SNPs are associated with an increased risk of developing specific diseases, such as heart disease, cancer, or diabetes. These genetic variants can provide insights into an individual’s genetic predisposition to particular health conditions.
Population Genetics: SNPs are used in population genetics studies to trace human migrations and evolutionary history. Patterns of SNP variation can help researchers understand the genetic diversity and relatedness of different populations.

[q] Describe reasons why a larger genome does not necessarily indicate presence of more genes.

[a] Non-Coding DNA: A significant portion of a genome consists of non-coding DNA. This non-coding DNA includes regulatory sequences, repetitive elements, and regions that do not code for proteins. While it plays important roles in gene regulation and genome stability, it does not contribute to the number of genes in an organism.
Gene Size: The size of individual genes can vary widely. Some genes are very large and code for complex proteins, while others are much smaller. The number of genes in a genome is not solely determined by the total amount of DNA but by the arrangement and size of the coding regions.
Gene Duplication: Gene duplication events can occur in a genome, leading to multiple copies of the same gene. These duplicated genes are often considered a single gene family, so even though there are more copies, they represent a single functional gene.

[q] State the units for measuring genome size.

[a] Base Pairs (bp)
Kilobase Pairs (Kbp or kb)
Megabase Pairs (Mbp or Mb)
Gigabase Pairs (Gbp or Gb)

[q] Define “sequence” in relation to genes and/or genomes.

[a] refers to the specific order of nucleotides (adenine, thymine, cytosine, and guanine, represented by the letters A, T, C, and G) in a DNA or RNA molecule. This sequence provides the genetic information necessary for the formation of proteins, regulation of gene expression, and the functioning of an organism. Sequences can vary between genes and among different individuals and species, and they play a crucial role in genetics and genomics research.

[q] List applications of genome sequencing.

[a] Disease Diagnosis: Identifying genetic mutations and variations associated with diseases, allowing for earlier diagnosis and personalized treatment.
Pharmacogenomics: Tailoring drug treatments to an individual’s genetic profile for more effective and safer medication.
Agriculture: Improving crop yields and disease resistance in agriculture through genomics-assisted breeding.
Forensic Science: Solving crimes by analyzing DNA evidence and identifying individuals through DNA profiling.
Evolutionary Studies: Tracing the evolutionary history of species and understanding genetic diversity.
Conservation: Protecting endangered species and biodiversity by studying their genomes.
Personalized Medicine: Customizing medical treatment based on an individual’s genetic makeup.