school slide Flashcards
What is meiosis?
A type of cell division that reduces the chromosome number by half, resulting in four haploid daughter cells.
How many nuclear divisions occur during meiosis?
Two nuclear divisions.
What is the chromosome number in daughter cells after meiosis?
Half of the number of chromosomes as the parent cell.
What are the two stages of meiosis?
- Meiosis I
- Meiosis II
What is another name for Meiosis I?
Reductional Division
What is another name for Meiosis II?
Equational Division
What occurs during interphase before meiosis?
Cell growth and DNA replication.
What are the three phases of meiotic interphase?
- G1 phase
- S phase
- G2 phase
What happens during the G1 phase?
Cell growth.
What occurs during the S phase?
DNA replication.
What is the purpose of the G2 phase?
Preparation for meiosis.
What happens during Prophase I?
Homologous chromosomes pair up and crossing over occurs.
How long does Prophase I last compared to Prophase in mitosis?
It takes about 85 - 95 percent of the total time for meiosis.
What are the five substages of Prophase I?
- Leptotene
- Zygotene
- Pachytene
- Diplotene
- Diakinesis
What occurs during the leptotene stage?
Chromatin condenses to form chromosomes.
What is synapsis?
The pairing of homologous chromosomes.
What is formed at the completion of the zygotene stage?
Bivalents.
What occurs during the pachytene stage?
Crossing over occurs.
What is a tetrad?
A group of four sister chromatids.
What happens during the diplotene stage?
DNA recombination is complete.
What is the significance of diakinesis?
Chromosomes become shorter and thicker due to condensation.
What occurs during Metaphase I?
All bivalents align at the metaphase plate.
What happens during Anaphase I?
Homologous chromosomes move to opposite poles.
What is the outcome of Telophase I?
Two distinct nuclei form around each set of chromosomes.
What is cytokinesis?
Division of the cytoplasm resulting in two haploid daughter cells.
What is interkinesis?
A phase similar to interphase between meiosis I and II.
List the important functions of meiosis.
- Reduction of chromosome number
- Genetic diversity
- Formation of gametes
- Maintenance of chromosome number
What does Meiosis II resemble?
A typical mitotic division.
What occurs during Prophase II?
The nuclear envelope breaks down and spindle apparatus forms.
What happens during Metaphase II?
Chromosomes align at the metaphase plate.
What occurs during Anaphase II?
Sister chromatids are pulled apart and move toward opposite poles.
What is the result of Telophase II?
Nuclear membrane reforms around each set of chromosomes.
What is the outcome of cytokinesis in Meiosis II?
Four haploid daughter cells are formed.
What is the purpose of mitosis?
Growth, repair, and asexual reproduction.
What is the difference in the number of daughter cells produced by mitosis and meiosis?
Mitosis produces two daughter cells, meiosis produces four.
What is gametogenesis?
The process by which gametes are produced.
What are the two types of gametogenesis?
- Spermatogenesis
- Oogenesis
Where does spermatogenesis occur?
In the testes.
What is the outcome of spermatogenesis?
Four viable sperm cells.
Where does oogenesis occur?
In the ovaries.
What is the outcome of oogenesis?
One viable ovum and three polar bodies.
What role do mitochondria play during meiosis?
They provide energy and are distributed to daughter cells.
What is mitochondrial inheritance?
The passing down of mitochondrial DNA exclusively from the mother.
What is the structure of mitochondrial DNA?
A small circular DNA molecule.
What can mutations in mitochondrial DNA lead to?
Mitochondrial diseases.
How is mitochondrial DNA used in genetics?
To trace maternal lineage and study evolution.
What are the four steps of natural selection?
Overproduction, Variation, Competition, Selection
Define convergent evolution.
Occurs when species of different ancestry share analogous traits due to similar environments or selection pressures.
What is divergent evolution?
An evolutionary pattern where two species gradually become increasingly different.
What is an example of divergent evolution?
The evolution of polar bears from a group of Brown bears that became geographically separated.
List the three types of evolution.
- Divergent
- Convergent
- Parallel
What is microevolution?
Small scale changes within species that produce new varieties or species in a relatively short time.
What are the mechanisms of evolution?
- Mutation
- Gene flow
- Genetic drift
- Natural selection
What is speciation?
The process by which new species arise.
List the types of speciation.
- Allopatric
- Sympatric
- Parapatric
What is macroevolution?
Large scale changes occurring over long periods, leading to new species formation.
What is natural selection?
The process where individuals better suited to their environment survive and reproduce.
True or False: Survival of the fittest means that only the strongest organisms survive.
False
What does ‘descent with modification’ imply?
Each living organism has descended, with changes, from other species over time.
Define parallel evolution.
Occurs when two species evolve independently while maintaining the same level of similarity.
What is adaptive radiation?
The evolution of many diversely adapted species from one ancestor.
What is the Hardy-Weinberg principle?
States that allele frequency remains constant if a population is not evolving.
List the five assumptions for Hardy-Weinberg equilibrium.
- No mutation
- Random mating
- No gene flow
- Very large population size
- No natural selection
What is artificial speciation?
The creation of new species by humans through laboratory experiments.
What is the fossil record?
Evidence of past life forms preserved in geological formations.
What are homologous structures?
Structures that develop from the same embryonic tissue but have different mature forms.
What is allopatric speciation?
Occurs when a physical barrier separates two groups of a species, preventing interbreeding.
What is peripatric speciation?
Similar to allopatric, but involves a small group breaking off from a larger population.
What is sympatric speciation?
Occurs without physical barriers, where new species develop in close proximity.
Give an example of sympathetic speciation.
The Midas cichlid in Lake Apoyo, which evolved to become a distinct species.
What is phylogenetics?
The study of evolutionary relationships among biological entities.
Why is molecular data important in phylogenetics?
It provides specific and rich information about evolutionary relationships.
List applications of phylogeny.
- Classification
- Forensics
- Identifying the origin of pathogens
- Conservation
- Bioinformatics and computing
What did Thomas Malthus contribute to Darwin’s theory?
He proposed that population growth leads to competition for resources.
Who was Russell Wallace?
He wrote an essay summarizing evolutionary change that motivated Darwin to publish his findings.
What is the significance of vestigial organs?
They are remnants of organs that have lost their original function.
What are some types of evidence for evolution?
- Fossil record
- Biogeography
- Vestigial structures
- Similarities in early development
- Biochemical evidence
What is the origin of the word ecology?
Derived from Greek words ‘Oikos’ meaning house and ‘Logos’ meaning to study.
How is ecology defined?
The scientific study of the relationship of living organisms with each other and their environment.
Who coined the term ecology and in what year?
Ernst Haeckel in 1869.
What is autecology?
The study of an individual species of organisms and its population.
What is synecology?
The study of communities, their composition, behavior, and relation with the environment.
Fill in the blank: Aquatic ecology is the study of interaction of organisms in _______.
water
What are the two main divisions of aquatic ecology?
Marine water ecology and Freshwater ecology.
What does terrestrial ecology study?
The interaction of organisms on land surfaces.
What is organism ecology?
The study of an individual organism’s behavior, morphology, and physiology in response to environmental challenges.
What factors does population ecology examine?
Factors that alter and impact the genetic composition and size of the population.
What is community ecology focused on?
How community structure is modified by interactions among living organisms.
What does ecosystem ecology study?
The entire ecosystem, including living and non-living components and their relationships.
What is landscape ecology concerned with?
The exchange of energy, materials, and organisms among ecosystems.
What does biosphere ecology study?
Interactions among Earth’s ecosystems, land, atmosphere, and oceans.
What defines an ecosystem?
A biological community where living and non-living components interact.
Name the two types of ecosystems.
- Natural ecosystem
- Artificial ecosystem
What are the major components of an ecosystem?
- Biotic components
- Abiotic components
What are biotic components?
Living organisms in an ecosystem, forming a community.
What are producers in an ecosystem?
Organisms that make their own food, primarily plants.
What role do consumers play in an ecosystem?
They get energy and nutrients by feeding on other organisms.
What are decomposers?
Organisms that break down dead organic material to recycle nutrients.
What are abiotic components?
Non-living chemical and physical components like water, air, and solar energy.
What are climatic factors in an ecosystem?
Factors such as rain, temperature, light, and wind.
What are edaphic factors?
Soil-related factors like pH, topography, and minerals.
What three parts make up the biosphere?
- Lithosphere
- Atmosphere
- Hydrosphere
What is the lithosphere?
The terrestrial part of the biosphere, supporting a variety of life.
What is the atmosphere?
The gaseous envelope surrounding Earth, also known as air.
What is the hydrosphere?
The aquatic part of the biosphere, including oceans and rivers.
Fill in the blank: The frozen part of Earth’s hydrosphere is called the _______.
cryosphere
What is the focus of study of species interactions?
The community
A community consists of all the populations of all the species in the same area and their interactions.
Define symbiosis.
A close relationship between two species in which at least one species benefits
The relationship can be positive, negative, or neutral for the other species.
What are the three basic types of symbiosis?
- Mutualism
- Commensalism
- Parasitism
How does energy enter ecosystems?
In the form of sunlight or chemical compounds.
What are producers and consumers in ecosystems?
- Producers (autotrophs) make food using energy
- Consumers (heterotrophs) obtain energy by eating producers.
What does the first law of thermodynamics state?
Energy cannot be created or destroyed; it can only change form.
What do food chains and food webs represent?
Feeding relationships from producers to consumers to decomposers.
What is a food chain?
A simple diagram that shows one way energy flows through an ecosystem.
What percentage of energy typically passes to the next level in a food chain?
About ten percent.
What happens to the energy that is lost at each level of a food chain?
- Given off as heat
- Goes into animal wastes
- Goes into growing non-consumable parts like fur.
What is a food web?
A representation of multiple pathways through which energy and matter flow through an ecosystem.
What is a community in the context of an ecosystem?
The biotic part of an ecosystem, consisting of all populations of species in the same area.
Define interdependence in ecology.
The reliance of living things on their environment and other organisms for survival.
What is predation?
A relationship where members of one species (the predator) consume members of another species (the prey).
What are the two types of competition?
- Intraspecific competition
- Interspecific competition
What is intraspecific competition?
Competition between members of the same species.
What is interspecific competition?
Competition between members of different species.
What does the term symbiosis mean?
Living together.
Define mutualism.
A symbiotic relationship in which both species benefit.
Provide an example of mutualism.
The relationship between goby fish and shrimp.
Define commensalism.
A symbiotic relationship in which one species benefits while the other is not affected.
Provide an example of commensalism.
Mites attaching to larger flying insects for a ‘free ride’.
What is parasitism?
A symbiotic relationship in which one species benefits (the parasite) while the other is harmed (the host).
Provide an example of a parasite.
Roundworms are parasites of mammals.
What does heredity refer to?
The passing of traits or characteristics through genes from one generation to the next.
What is genetics?
A branch of science that studies the DNA, genes, genetic variation, and heredity in living organisms.
What is inheritance?
Acquiring characteristics or traits from one generation to the other.
Who is known as the ‘Father of Genetics’?
Gregor Johann Mendel.
What are Mendel’s Laws of Inheritance?
Law of Dominance, Law of Segregation, Law of Independent Assortment.
What does the Law of Dominance state?
A gene has two contrasting alleles and one always expresses itself in the organism.
What does the Law of Segregation state?
Traits get segregated completely during the formation of gametes without any mixing of alleles.
What does the Law of Independent Assortment state?
Traits can segregate independently of different characters during gamete formation.
Define traits.
Characteristic features of an organism, manifested in a physical form or physiological aspect.
What is a gene?
The basic unit of inheritance, consisting of a sequence of DNA.
What are alleles?
Alternative forms of genes affecting the same characteristics, located on the same chromosome.
What are chromosomes?
Thread-like structures made of DNA and proteins that carry hereditary or genetic information.
What is DNA?
A self-replicating material present in nearly all living organisms, serving as the main constituent of chromosomes.
Define genotype.
The complete heritable genetic identity of an organism, including non-expressed alleles.
Define phenotype.
The description of the actual physical characteristics of an organism.
What are dominant alleles?
Alleles that affect the phenotype and are represented by capital letters.
What are recessive traits?
Traits that are not expressed in the presence of a dominant allele.
What is a homozygous organism?
An organism with two identical alleles for a gene.
What is a heterozygous organism?
An organism with two different alleles for a gene.
Fill in the blank: The traits acquired over an organism’s lifetime are termed as _______.
acquired characters.
Fill in the blank: The traits inherited from parents are called _______.
inherited characters.
What is a monohybrid cross?
A cross between two plants with one pair of contrasting characters.
What is the phenotypic ratio in the F2 generation of a monohybrid cross?
3:1 (3 tall: 1 short).
What is a dihybrid cross?
A cross between two plants with two pairs of contrasting characters.
What is the phenotypic ratio in the F2 generation of a dihybrid cross?
9:3:3:1.
What is sex determination?
The process of determining the sex of an individual based on genetic material.
What are genetic variations?
Differences in DNA sequences among organisms that lead to a diverse gene pool.
What is a congenital disorder?
Structural or functional anomalies that occur during intrauterine life.
What does the human genome refer to?
All of the approximately three billion base pairs of DNA that make up the entire set of chromosomes of the human organism.
Define evolution.
The theory in biology that postulates the origin of various types of living things through modifications in successive generations.
What is natural selection?
The phenomenon where favorable traits in a population are selected for survival and reproduction.
What is an endangered species?
Any species at risk of extinction due to a rapid decrease in population or loss of habitat.
What is genetic drift?
A change in the frequency of an existing allele in a small population.
What are fossils?
Preserved remains of ancient organisms that provide evidence for the theory of evolution.
What is the biological process by which organisms give rise to their own kind?
Reproduction
Reproduction allows organisms to pass their traits to their offspring.
What are the two main types of reproduction?
- Asexual reproduction
- Sexual reproduction
What term describes reproduction that occurs with a single individual?
Asexual reproduction
What is sexual reproduction?
A process where male gamete fuses with female gamete to create a new individual.
Which organisms commonly reproduce asexually?
- Bacteria
- Protozoa
- Some algae
What is binary fission?
A type of asexual reproduction where a cell divides to form two individuals.
In which organisms does budding occur?
- Yeast
- Hydra
- Sponges
What is spore formation?
A method of asexual reproduction where spores develop into new individuals.
What is vegetative propagation?
A form of asexual reproduction in plants where new plants arise from vegetative parts.
What is artificial propagation in plants?
Human methods to grow plants inspired by natural vegetative propagation.
What is cloning?
Creating a genetic copy of the parent organism.
What is the reproductive organ of flowering plants?
The flower
What are stamens?
The male part of a flower that produces pollen.
What is pollination?
The transfer of pollen grain from anther to stigma of a flower.
Define self-pollination.
When pollen from a flower falls on its own stigma.
What is cross-pollination?
Pollen from one flower fertilizes the ovule of another flower of the same species.
What are the two main types of reproduction in animals?
- Asexual reproduction
- Sexual reproduction
What is viviparous reproduction?
Reproduction where the baby develops inside the mother’s womb.
What are hermaphrodites?
Organisms that possess both male and female sex organs.
What is adolescence?
The stage of life when a person undergoes physical and hormonal changes leading to reproductive maturity.
At what age does puberty typically begin in humans?
Around 10-11 years of age.
What are the three types of changes experienced during adolescence?
- Physical
- Physiological
- Psychological
What are some psychological changes that occur during adolescence?
- Capability of abstract thinking
- Mood swings
- Importance of self-image
- Interest in friendships and romantic relationships
True or False: Humans are viviparous.
True
Fill in the blank: The period between birth and maturity is very short in _______.
[animals]
What is the importance of relationships during adolescence?
Building relationships based on equality, mutual respect, and love.
