4.1 - 4.6 : Biodiversity Flashcards
What is the statement on the spec for 4.1 ?
‘over time the variety of life has become extensive but is now being threatened by human activity’.
Define the term habitat
The place where an organism lives
Define the term biodiversity.
The measure of the variety of living organisms present within a particular area
What is meant by the term endemism ?
When a species is only found in one geographical location.
- The Malabar climbing frog is endemic because there is just a single population living in India. Endemic species are vulnerable to extinction.
What is the heterozygosity index used for ?
It is used to measure genetic diversity within a population. It tells us the proportion of individuals that have different alleles (heterozygous) at a particular gene.
In simple terms, it helps scientists understand:
1. How genetically diverse a population is (more diversity means a higher heterozygosity index).
2. Whether the population is healthy and capable of adapting to changes (higher diversity often means better survival chances)..
The higher the number of heterozygotes, the higher the genetic diversity.
What is the formula for heterozygosity index (H) ?
What is the index of diversity (D) ?
It calculated the diversity in a habitats. It takes into account both the number of different species and the abundance of each species.
- The larger the value of diversity index, the more diverse the habitat is .
- If all the individuals are of the same species
(i.e. no biodiversity) the index is 1.
What is the formula for the index of diversity (D) ?
What are the three types of adaptations ?
- Behavioural (Changes to actions) - e.g hibernation, migration, altered feeding habits and distinct modes of communication. Often crucial for finding food, avoiding predators, or communicating with others.
- Physiological (changes to bodily/internal processes that help the organism to survive) - e.g venom production, temperature regulation, metabolic rate
- Anatomical (**changes to body structure **which increases its chances of survival) - e.g oily fur, polar bears are camouflaged against the snow and cacti have spines to prevent being eaten by animals.
Click here for better explanation link
What is meant by the term niche ?
The role that an organism plays in the environment and includes its biotic and abiotic factors.
- Within the same habitat, different organisms will have different niches. If two different organisms occupy the same niche, one will be out-competed by the other until one species survive.
What is meant by the term natural selection.
The process which an organism adapts to its environment through selectively reproducing changes in its genotype. The organisms with the best suited characteristics for their environment are more likely to survive and reproduce.
Explain how natural selection results in adaptation and evolution.
- Variation - There is variation within the population. Gene mutations cause new alleles to appear in the population - some of these may be harmful but some may be beneficial or environmental factors or both.
- Selection pressure - Environmental factors such as predation, competition for resources, diseases or climate change create a selection pressure on the population.
- Survival of the fittest - Individuals who are best adapted to the environment are more likely to survive and reproduce.
- Reproduction - The ones that survive reproduce and pass on their alleles to their offspring, and therefore posses new adaptations that allow them to survive in their environment.
Evolution : The frequency of the advantageous allele increase in the population. This is evolution.
How can we measure species diversity ?
Explain the term species richness.
The number of species in a community.
What is the Hardy-Weinberg principle ?
It allows us to estimate the frequency of alleles in a population, as well as if the frequency is changing over time.
It predicts that the allele frequency will not change between generations.
What does the term speciation refer to ?
Speciation refers to the development of a new species.
- It occurs when **two* groups of the population become reproductively isolated from each other.
What does reproductive isolation prevent.
- Reproductive isolation prevents the transfer of genes (reduced gene flow) between the two groups so natural selection acts separately on the two sub populations.
What are the two types of speciation ?
Allopatric and Sympatric.
What can reproductive isolation lead to ?
reproductive isolation can lead to accumulation of different
genetic information in populations, potentially leading to the formation of new species.
Define the term allele frequency
How offended an allele occurs in a population.l
What assumptions does the Hardy-weinberg principal make ?
- The population is large
- No immigration or emigration is occurring
- Mating is random
- No new mutations have arisen
- No natural selection has occurred
What can we understand if the allele frequencies change from one generation to the next within a large population.
If the allele frequencies change from one generation to the next within a large population, then we know that mutation, migration, non-random mating or natural selection has taken place.
What do we use the hardy-Weinberg equations for ?
To predict allele frequency.
- When a gene has two alleles, you can figure out the frequency of one of the alleles of the gene if you know the frequency of the other allele.
To predict genotype and phenotype frequency.
What are the hardy weinberg equations ?
Watch here for better understanding. link
What are the consequences of reproductive isolation ?
Allopatric speciation
Occurs when populations are geographically this prevent groups from mating.
Causes reproductive isolation
If polyation sizes are small random mutations can cause genetic drift.
What is classification.
is a means of organising the variety of life based on relationships between organisms using differences and similarities in phenotypes and in genotypes, and is built around the species concept
What is taxonomy
The grouping of organisms according to their characteristics.
What is the order of taxonomic groups.
Dear King Phillip Came Over For Good Soup.
How are species named ?
What is the classification of organisms dependent on ?
- Their phenotypes, genotypes and how related they are.
How did early classification systems place organisms into groups ?
They used observable phenotypes.
What is molecular phylogeny ?
The study of molecules (DNA and proteins ) to see how closely related organisms are, e.g more closely related organs have more similar molecules.
How does new data help in terms of classification ?
It can help to reclassify organisms in a more accurate category.
Name examples of when new data had help for the reclassification of organisms
When the domain classification system (which are bacteria, archaea and eukaryote) was proposed due to molecular phylogeny.
