Biology Chapter on Genetic Diversity

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What are the two main sources of genetic diversity?

Genetic drift and recombination

Meiosis and gene flow

Natural selection and mutations

Mutations and meiosis (correct)

Which process during meiosis contributes to genetic diversity through allele exchange?

Crossing over (correct)

Mutation

Independent assortment

Fertilization

What does the term species richness refer to?

The proportion of endemic species in a region

The genetic variability within a species

The total number of organisms in an ecosystem

The total number of different species in a given area (correct)

What is a consequence of a population falling below 50 breeding adults?

Genetic inbreeding and harmful recessive alleles Signup and view all the answers

Which index is used to estimate species diversity statistically?

Simpson's Biodiversity Index Signup and view all the answers

Which kingdom is characterized by prokaryotic cells?

Prokaryotes Signup and view all the answers

In which kingdom do organisms primarily obtain nutrition through autotrophic means?

Plants Signup and view all the answers

Which kingdom includes organisms that can both move freely and cannot move?

Protoctista Signup and view all the answers

Organisms in which kingdom are almost always reproduced sexually?

Animals Signup and view all the answers

Which kingdom's cells are characterized by complex tissues?

Plants Signup and view all the answers

Which of the following kingdoms includes organisms that can be single-celled and multicellular?

Protoctista Signup and view all the answers

What type of nutrition do most fungi exhibit?

Heterotrophic Signup and view all the answers

Which kingdom does not display organization into tissues?

Prokaryotes Signup and view all the answers

What is the primary purpose of anatomical adaptations in organisms?

To help organisms survive or reproduce Signup and view all the answers

Which statement best defines a gene pool?

All the alleles of all the genes in a population at a certain time Signup and view all the answers

Which of the following is NOT an assumption of the Hardy-Weinberg equation?

The population is experiencing frequent mutations Signup and view all the answers

How does genetic diversity benefit a population?

It reduces the chance of extinction Signup and view all the answers

What typically triggers a change in selection pressures in a population?

A change in the environment affecting resources Signup and view all the answers

Which process contributes to genetic variation in a population?

Crossing over during meiosis Signup and view all the answers

What is NOT a component required for the genetic diversity of a population?

Equal distribution of alleles Signup and view all the answers

Which of the following is an example of a historical adaptation that enhances survival due to environmental pressures?

Large ears in elephants for heat dissipation Signup and view all the answers

What is the first step in the drug testing process?

Pre-clinical testing Signup and view all the answers

What is the primary purpose of clinical trials phase 3?

Get statistical evidence on drug effectiveness Signup and view all the answers

During the mass testing of fibres, what is the first step before adding weights?

Hang a mass holder from a single fibre Signup and view all the answers

Why is temperature control essential in bacterial growth?

It ensures efficient enzyme reactions Signup and view all the answers

What is the role of moisture in bacterial growth?

Facilitates chemical reactions like respiration Signup and view all the answers

What aspect characterizes double-blind trials in clinical testing?

Both researchers and patients are unaware of treatments Signup and view all the answers

What type of studies are conducted during the pre-clinical testing phase?

Animal studies and tissue cultures Signup and view all the answers

Why is oxygen important for bacterial growth?

It is necessary for aerobic respiration Signup and view all the answers

Which of the following accurately describes the cell wall composition in some organisms?

Some organisms have chitin in their cell walls, while others have peptidoglycan. Signup and view all the answers

In the three domains theory proposed by Woese, which domain is classified as prokaryotic?

Bacteria Signup and view all the answers

What is the primary function of chloroplasts in plant cells?

Site of photosynthesis Signup and view all the answers

What structural characteristic of cellulose contributes to its high tensile strength?

Chains of beta-glucose molecules are straight and unbranched. Signup and view all the answers

What role does the tonoplast play in plant cells?

Membrane around the vacuole. Signup and view all the answers

Which statement accurately reflects the relationship between Archaea and Eucarya?

Archaea and Eucarya share more similarities than either shares with Bacteria. Signup and view all the answers

What is the first step in investigating the antimicrobial properties of plants?

Make a plant extract from 5g of plant material Signup and view all the answers

What is the function of plasmodesmata in plant cells?

To allow movement of dissolved substances between cells. Signup and view all the answers

Which of the following characteristics correctly distinguishes eukaryotic cells from prokaryotic cells?

Eukaryotic cells have linear DNA with histone proteins. Signup and view all the answers

Why is it important to incubate the agar plate at 25°C?

It allows non-pathogenic bacteria to outcompete pathogenic bacteria. Signup and view all the answers

What is the purpose of the ethanol control disc in the experiment?

To serve as a baseline for comparison with plant extracts. Signup and view all the answers

How should filter paper discs be prepared before placing them on the agar plate?

They should be soaked in the plant extract and allowed to dry. Signup and view all the answers

Which of the following is a reason why oil-based fuels are not sustainable?

They contribute to long-term resource depletion. Signup and view all the answers

Which safety precaution should be taken during the practical investigation?

Tie back hair to avoid fire hazards. Signup and view all the answers

In measuring the effectiveness of the plant extracts, what does a larger clear zone indicate?

The extract has stronger antibacterial properties. Signup and view all the answers

What does the principle of sustainability emphasize?

Ensuring resource use does not harm the environment long-term. Signup and view all the answers

Study Notes

Defining Biological Terms

Species: A group of organisms that can interbreed to produce viable, fertile offspring (e.g., Grey squirrels, Hazel trees).
Population: All the organisms of one species in a particular place at a particular time (e.g., the Human population of Britain in 2014).
Community: All the populations of all the species in a particular place at a particular time (i.e., all life in an area including animals, plants, fungi, bacteria...everything living).
Habitat: The place, with a distinctive set of conditions, where an organism lives.
Niche: The role an organism plays in its environment or how an organism exploits (uses) its environment. Most importantly it describes what it eats/where it is located in a food chain/its trophic level. But it also includes where it shelters and the times it is active. Only one species can survive in a single niche. If a second species inhabits exactly the same niche they will compete and one species will die out.
Environment: The external surroundings including all of the biotic (living) and abiotic (non-living) factors.
Interspecific Competition: Competition for resources (e.g., light, space, food, minerals) between individuals of different species.
Intraspecific Competition: Competition for resources (e.g., light, space, food, minerals) between individuals of the same species.

Adaptations

Behavioral Adaptations: Actions by an organism that help them to survive or reproduce. Examples include hibernation, migration, hunting strategies, herding together for protection, burying acorns to store food for winter.
Physiological Adaptations: Features of an organism's body chemistry that help them survive or reproduce. Examples include chemicals acting as pigments for coloration, modified hemoglobin to work at high altitudes, venom, anti-venom, digestive enzymes, and bacterial with thermostable enzymes.
Anatomical Adaptations: Structures that an organism has that help them survive or reproduce. Examples include lungs adapted to have a large surface area, muscles in arterioles to adjust rate of blood flow to particular organs, antlers on deer, claws, and large ears on an elephant.

Natural Selection

Natural Selection Steps:
A population has naturally-occurring genetic variation with new alleles created through mutations.
A change in the environment causes a change in the selection pressures acting on the population.
An allele which was previously of no particular advantage now becomes favorable.
Organisms with the allele are more likely to survive, reproduce, and so produce offspring.
Their offspring are more likely to have the allele, so it becomes more common in the population.

Gene Pool and Genetic Diversity

Gene Pool: All the alleles of all the genes in a population at a given time.
Genetic Diversity: The variety of alleles in a gene pool (often derived from meiosis – crossing over, independent assortment – or from mutations and random fertilization). The more different alleles there are in a gene pool, the greater the genetic diversity.

Hardy-Weinberg Equation Assumptions

Large Population: To prevent in-breeding effects
Random Mating: Individuals with a particular genotype must not tend to mate with other individuals of the same genotype.
No Selection: This would affect the frequency of particular alleles.
No Mutations: This would affect the frequency of particular alleles.
No Immigration/Emigration (Gene Flow): No gene flow into or out of the population – as this would affect the frequency of particular alleles.

Biodiversity

Biodiversity Components:
Genetic Diversity: A measure of the variety of alleles in a gene pool (tends to increase over time as mutations accumulate, meiosis).
Species Diversity: The number of individuals and the number of species in a community (should increase over time).

Sources of Genetic Diversity

Mutations to DNA: Either by a mutagen (e.g., ionizing radiation, toxins from cigarette smoke) or randomly by inaccurate copying of DNA during the S phase of the cell cycle.
Meiosis:
Crossing Over: When non-sister chromatids exchange alleles.
Independent Assortment: Homologous pairs line up at the equator, but their orientation with respect to maternal and paternal chromosomes is random.

Defining Biodiversity Terms

Species Richness: The number of different species present in a particular habitat at a particular time – but tells us nothing about their abundance.
Biodiveristy: Made up of 2 main components: Genetic diversity - there is genetic variation between members of a species. However, if a population falls below the level of 50 breeding adults, there is likely to be genetic inbreeding, usually resulting in the accumulation of harmful recessive alleles. Species diversity - a measure of both the number of individuals and the number of species in a community.
Endemism: Where an organism's distribution is restricted to specific geographical areas. Islands which have been isolated for a long time often have endemic species. The longer the isolation, the greater the number of endemic species present.

Simpson's Biodiversity Index

A statistical test (Simpson's Biodiversity Diversity Index) can quantify species diversity.
Its formula involves the total number of organisms of all species and the total number of organisms of a particular species.

Plant Cell Organelles

Cell Wall: Provides support and protection.
Chloroplasts: Site of photosynthesis
Amyloplasts: Storage of starch.
Vacuole: Contains cell sap. Keeps cells turgid when water enters.
Tonoplast: The membrane around the vacuole.
Plasmodesmata: Allows movement of dissolved substances directly from one cell to another without having to pass through the cell membrane.
Pits: Areas of very thin cell walls that help movement of substances between cells.
Middle Lamella: The layer between the cell walls of adjacent cells.

Cellulose Structure and Function

Cellulose has a high tensile strength due to its structure. It is made of beta-glucose, joined by beta(1-4) glycosidic bonds. Cellulose molecules are unbranched and straight. Many lie next to each other, bonded with hydrogen bonds. This forms microfibrils. Cellulose is also insoluble in water due to its large size.

Starch vs Cellulose

Feature	Starch	Cellulose
Monomer	Glucose	Glucose
Specific type of monomer	Alpha-glucose	Beta-glucose
Types of bond present	Alpha(1-4) glycosidic bonds, Alpha(1-6) glycosidic bonds	Beta(1-4) glycosidic bonds, Hydrogen bonds between cellulose molecules
Branching	Yes (in amylopectin)	No
Location in plant cell	Amyloplasts	Cell wall
Function in plants	Storage of glucose (to be used to make new cell wall or to provide energy through respiration)	Structural. Supports plant cells
Solubility	Insoluble	Insoluble

Xylem Vessels, Phloem Sieve Tubes, and Sclerenchyma Fibres in Plant Stems

Vascular bundles are near the outer edge of the stem.
Sclerenchyma is outermost.
Then phloem.
Then xylem

Xylem Vessels Structure and Function

Xylem is tissue that transports water and mineral ions from the root to the stems and leaves, and supports the stem.
Xylem vessels are large cells with thick cell walls (like drain pipes)
The cross walls are missing, allowing a structure that acts like a continuous tube for water transport in one direction
The walls are strengthened with lignin, making them waterproof and supporting the plant
The tonoplast breaks down and the cell contents dissolve (dead cells)

Phloem Structure and Function

Phloem transports products of photosynthesis (sucrose and other organic solutes) from leaves to other plant parts.
Phloem is made of sieve tubes and companion cells.
Sieve tubes are long, individual cells arranged end-to-end, perforated walls (sieve plates), allowing fluid movement between lumens of adjacent cells .
Companion cells have a lot of ribosomes and mitochondria, and their cellular functions support the activities of the sieve elements.

Sclerenchyma Fibres Structure and Function

Sclerenchyma fibres are a type of supporting tissue in plants.
They have very thick cell walls, strengthened with lignin, small lumen.
They lack cytoplasm and are dead cells.
They are different from xylem vessels because they have cross-walls and don’t form tubes.

Measuring Mineral Deficiencies in Plants

Method steps:
1. Prepare solutions with different mineral concentrations or a mineral missing.
2. Maintain all conditions constant except the mineral being investigated.
3. Cover the tops of test tubes with a clear film above the solution. Attach the seedling with roots in the solution and stem out.
4. Use 10 repeats per solution
5. Control temperature and light intensity.
6. Control for the age of seedling for consistent results
7. Leave to grow for 3 weeks.
8. Measure changes in length, stem mass, number of leaves, and colour to evaluate results.

Inorganic Ions Required by Plants

Nitrate ions: Needed to make amino acids, proteins, chlorophyll, and nucleic acids; deficiency causes stunted growth and yellow leaves.
Magnesium ions: Needed to make chlorophyll; deficiency causes yellow leaves but veins remain green.
Calcium ions: Needed to build cell walls, pectins, and for cell membrane permeability; deficiency causes stunted growth and misshapen leaves.

Measuring Tensile Strength of Plant Fibres

Method steps:
1. Extract plant fibres from standardized way - e.g. retting or scraping.
2. Use plants of the same age/ leaves collected the same time ago.
3. Attach the plants to a clamp with a hook
4. Add increasing mass to the fibres and see what mass makes the fibre break
5. Repeat these steps 10 times for each plant fibre type.
6. Control for temperature and humidity.

Drug Testing Process

Pre-clinical Testing: Animal studies and tissue cultures identify active ingredients. Tests for safety and toxicity.
Phase 1: Small group of healthy volunteers checks for safety in humans. Identifies side effects and maximum tolerated dose.
Phase 2: Small group of patients with the illness tests for treatment effectiveness.
Phase 3: Large group of patients with the illness, double blind tests for treatment effectiveness testing a new drug against a placebo to identify statistically significant results.
Post-licensing: Data collection continues once the drug is licensed to identify rare or long-term side effects and ensure the clinical trials were correct.

Conditions for Bacterial Growth

Warm temperature: For efficient enzyme reactions.
Moisture: For chemical reactions (like respiration).
Oxygen (Aerobic Bacteria Only): For aerobic respiration.
pH: For efficient enzyme reactions.

Investigating Antimicrobial Properties of Plants

Method steps:
1. Prepare a plant extract. (e.g., 5g of plant material in 10cm³ ethanol)
2. Soak filter paper discs into the extract. Dry.
3. Prepare a bacterial lawn on an agar plate.
4. Place dried discs onto the agar plate seeded with bacteria.
5. Tape the lid of the agar plate in quarters to prevent opening.
6. Incubate at a controlled temperature (25°C).
7. Observe and measure the zone of inhibition around each disc.
8. Repeat the experiment at least 10 times for each plant.
9. Compare the mean sizes of the clear zones around each disc.
10. Greater zone size = more effective antimicrobial properties. Measure clear zones (diameters).

Sustainability

Sustainability: The principle that the use of resources (or the environment in general) should only be permitted if it can be done without damaging the environment or reducing those resources in the long term.

Fossil Fuels as Carbon Sinks

Carbon Sink: A long-term store of carbon where carbon is prevented from cycling around the carbon cycle.
Dead plant or animal matter in anaerobic conditions (e.g., swamps, bottom of the sea) doesn't decay.
This matter is turned into fossil fuels (coal, oil, gas).
Carbon in fossil fuels stays there for long time, preventing its release back into the environment.
However, combustion releases this carbon into the atmosphere as carbon dioxide.

Captive Breeding Programs

Increasing Population: Increase the number of individuals of a species successfully.
Maintaining Genetic Diversity: Collect data on individuals and decide which ones to breed together. Collaborate with other zoos to increase the effective population size (minimum 50 individuals).
Reintroduction: Train animals in captivity. Over exposure to humans might affect behaviour and chances of survival in the wild.

Seed Bank Storage Processes

Seed Collection: Collect seeds from the wild, identifying the species.
Viability Check: X-ray seeds to check for embryo presence/ viability.
Preparation: Dry, sterilize, and package seeds.
Storage: Store seeds in large numbers at low temperatures (-20°C) to prevent germination and decomposition.
Monitoring: Periodic germination trials to check seed viability.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on genetic diversity and organism classification in this biology quiz. Explore key concepts such as species richness, kingdoms of life, and the processes contributing to genetic variation. Perfect for students delving into biological sciences and genetics.