Comprehensive Biology: Cell Division, Genetics, Evolution, and Ecology

What distinguishes benign tumors from malignant tumors?

Benign tumors are noncancerous and do not invade other tissues, while malignant tumors are cancerous and can spread.

What are the main reasons cells divide?

To grow, repair damage, replace old cells, and reproduce.

What is the difference between prokaryotic and eukaryotic cells?

Prokaryotes have no nucleus and divide by binary fission, while eukaryotes have a nucleus and divide by mitosis or meiosis.

Why is the surface area-to-volume ratio important for cells?

Cells with a higher surface area-to-volume ratio can transport materials faster and exchange nutrients and waste more efficiently.

What happens during the G1 phase of the cell cycle?

The cell grows and prepares for DNA replication.

What occurs during the S phase of the cell cycle?

DNA replicates, resulting in two identical copies of each chromosome.

What is the purpose of the M phase in the cell cycle?

Mitosis divides the nucleus, and cytokinesis splits the cytoplasm, resulting in two identical daughter cells.

What are the stages of mitosis, represented by PMAT?

Prophase, Metaphase, Anaphase, Telophase.

What is the role of the centromere during mitosis?

It holds and connects sister chromatids and is where spindle fibers attach.

What did Redi's experiment demonstrate regarding spontaneous generation?

Maggots come from flies laying eggs, disproving the idea of spontaneous generation.

What was the conclusion of Pasteur's swan-neck flask experiment?

Microorganisms come from other microorganisms in the air, not spontaneous generation.

What is the function of a light microscope?

To view living cells at lower magnifications using visible light.

What is the significance of Frederick Griffith's transformation experiment?

It showed that genetic information can be transferred between bacteria.

What did Avery, MacLeod, and McCarty demonstrate about DNA?

They showed that DNA is the transforming factor responsible for genetic information.

What are the components of a nucleotide?

A phosphate group, a sugar, and a nitrogen base (A, T, C, or G).

What is the process of DNA replication?

Helicase unzips DNA, DNA polymerase adds nucleotides, and DNA ligase seals fragments.

What is the central dogma of molecular biology?

It explains the flow of genetic information: DNA → RNA → Protein.

What is the role of RNA polymerase in transcription?

It unzips DNA and builds a complementary mRNA strand.

What are histones and their role in gene expression?

Histones are proteins that DNA wraps around, helping package DNA and regulate gene expression.

What are point mutations and their types?

Changes in one nucleotide; types include silent, missense, and nonsense mutations.

What is the difference between diploid and haploid cells?

Diploid cells (2n) have two sets of chromosomes, while haploid cells (n) have one set.

What is the purpose of meiosis?

To produce gametes, increase genetic variation, and reduce chromosome number from diploid to haploid.

What happens during Meiosis I?

The cell separates homologous chromosomes, going from diploid (2n) to haploid (n).

What occurs during Prophase I of meiosis?

Crossing over occurs, where homologous chromosomes exchange pieces of DNA, increasing genetic variation.

What happens during Metaphase I of meiosis?

Homologous pairs line up in the middle randomly, increasing variation through independent assortment.

What is the outcome of Anaphase I in meiosis?

Homologous chromosomes separate, with one chromosome from each pair going to opposite sides, while sister chromatids stay together.

What is formed at the end of Telophase I?

Two cells are formed.

How does Meiosis II differ from Meiosis I?

Meiosis II is similar to mitosis but occurs in haploid cells, separating sister chromatids to produce 4 genetically different haploid cells.

What is crossing over?

The process where homologous chromosomes swap DNA segments, creating new combinations of genes.

What is independent assortment?

The random arrangement of homologous pairs during Metaphase I, leading to different mixes of maternal and paternal chromosomes in gametes.

What is random fertilization?

The process where any sperm can fertilize any egg, contributing to genetic uniqueness in offspring.

What is a karyotype?

A picture of all the chromosomes in a cell, arranged in pairs from largest to smallest, used to count chromosomes and detect abnormalities.

What are the characteristics of a human karyotype?

Humans have 46 chromosomes, arranged in 23 homologous pairs.

What is Mendel's Law of Segregation?

Alleles separate during meiosis, ensuring that gametes receive one allele from each pair.

What does Mendel's Law of Independent Assortment state?

Different genes assort independently during gamete formation.

What is the difference between homozygous and heterozygous?

Homozygous has two identical alleles (AA or aa), while heterozygous has two different alleles (Aa).

What is incomplete dominance?

A genetic scenario where neither allele is completely dominant, resulting in a blended phenotype, such as red and white flowers producing pink offspring.

What is codominance?

A genetic scenario where both alleles are expressed simultaneously, such as in AB blood type.

What is polygenic inheritance?

A trait influenced by many genes, resulting in a wide range of phenotypes, such as height and skin color.

What is epistasis?

A situation where one gene affects the expression of another gene, potentially masking its effects.

What is the Hardy-Weinberg Equilibrium?

A principle stating that a population is not evolving if there are no mutations, migration, random mating, a large population, and no natural selection.

What are the conditions for natural selection?

Variation, inheritance, overproduction, and competition among individuals for limited resources.

What is the bottleneck effect?

A drastic reduction in population size due to a disaster, leading to decreased genetic diversity.

What is the founder effect?

When a small group starts a new population, leading to reduced genetic variation.

What is stabilizing selection?

A type of natural selection that favors average phenotypes, reducing variation.

What is directional selection?

A type of natural selection that favors one extreme phenotype, causing a shift in the population's traits.

What is disruptive selection?

A type of natural selection that favors extreme phenotypes at both ends of the spectrum.

What is antibiotic resistance?

An example of natural selection where bacteria evolve to survive exposure to antibiotics.

How does antibiotic resistance spread in bacteria?

Resistant bacteria survive antibiotic treatment, reproduce, and pass resistance genes to their offspring.

What is microevolution?

Small changes within a population that do not result in the formation of a new species.

What is speciation?

The formation of new species when populations become so different that they can no longer successfully reproduce.

What are isolation mechanisms?

Factors that prevent populations from mating, leading to speciation, such as behavioral, temporal, and mechanical isolation.

What is adaptive radiation?

The process where one ancestral species evolves into many species adapted to different niches, exemplified by Darwin's finches.

What is the mnemonic for the taxonomic hierarchy?

King Phillip Comes Over For Great Sex (Kingdom, Phylum, Class, Order, Family, Genus, Species).

What do phylogenetic trees and cladograms illustrate?

They show evolutionary relationships between organisms, indicating how closely related they are based on common ancestry.

What are homologous structures?

Structures that share a common ancestry, providing evidence of evolutionary relationships.

What are analogous structures?

Structures that have the same function but different ancestries, indicating convergent evolution.

What is the basic level of organization in biological systems?

Cell → Tissue → Organ → Organ System → Organism.

What are the three embryonic germ layers?

Ectoderm (skin and nervous system), Mesoderm (muscles, bones, blood), Endoderm (digestive tract and lungs).

What are totipotent cells?

Cells that have the potential to become any cell type, such as a fertilized egg.

What is homeostasis?

The process of maintaining stable internal conditions in an organism.

What is the path of air in the respiratory system?

Nose/Mouth → Pharynx → Larynx → Trachea → Bronchi → Bronchioles → Alveoli.

What occurs in the alveoli?

Gas exchange, where oxygen enters the blood and carbon dioxide is expelled.

How does inhalation occur?

The diaphragm contracts, lowering pressure in the thoracic cavity, allowing air to enter.

How is oxygen transported in the blood?

Oxygen binds to hemoglobin in red blood cells, forming oxyhemoglobin.

What is the function of arteries?

To carry blood away from the heart, usually oxygen-rich, except for the pulmonary artery.

What are the three main types of blood vessels?

Arteries, veins, and capillaries.

What is the role of the nervous system in homeostasis?

It detects stimuli, processes information, and coordinates responses to maintain stable internal conditions.

What are biotic and abiotic factors?

Biotic factors are living components of an ecosystem, while abiotic factors are nonliving components.

What is exponential population growth?

A J-shaped curve representing unlimited resources leading to rapid population increase.

What are limiting factors in population growth?

Factors that restrict population size, which can be density-dependent (e.g., disease) or density-independent (e.g., natural disasters).

What is mutualism?

A type of community interaction where both species benefit, such as bees pollinating flowers.

What is a keystone species?

A species that has a disproportionately large impact on its ecosystem, and its removal can drastically alter the ecosystem.

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