Comprehensive Biology Review: Cellular Energy, Mitosis, DNA, Evolution & Classification

What are the key components of an ATP molecule, and how does it release energy to become ADP?

ATP consists of adenine, ribose, and three phosphate groups. It releases energy when the bond between the second and third phosphate groups is broken via hydrolysis, converting it into ADP and a free phosphate.

What is the balanced chemical equation for photosynthesis, and what is its primary energy source?

6CO₂ + 6H₂O + light energy → C₆H₁₂O₆ + 6O₂. The primary energy source is sunlight.

Which major groups of organisms possess the ability to perform photosynthesis?

Plants, algae (protists), and certain bacteria (such as cyanobacteria).

What is the balanced chemical equation for aerobic cellular respiration, and what is its ultimate biological purpose?

C₆H₁₂O₆ + 6O₂ → 6CO₂ + 6H₂O + ATP. Its purpose is to break down glucose to generate usable chemical energy (ATP) for cellular work.

During which specific stage of cellular respiration is the vast majority of ATP generated, and where does it take place?

The Electron Transport Chain (ETC) / Oxidative Phosphorylation, which takes place across the inner mitochondrial membrane (cristae).

How do cancer cells differ fundamentally from normal cells regarding the cell cycle?

Cancer cells have mutated genes that cause them to lose the ability to regulate their cell cycle, leading to uncontrolled cell division and the avoidance of apoptosis.

Why are stem cells uniquely important in biology and medicine?

They are unspecialized cells capable of renewing themselves through cell division and can differentiate into various specialized cell types under appropriate conditions.

Contrast a parent cell with its daughter cells at the end of mitosis in terms of cell count and chromosome number.

Mitosis starts with 1 diploid parent cell and ends with 2 genetically identical diploid (2n) daughter cells. The chromosome number remains exactly the same.

Contrast a parent cell with its daughter cells at the end of meiosis in terms of cell count and chromosome number.

Meiosis starts with 1 diploid parent cell and ends with 4 genetically diverse haploid (n) daughter cells. The chromosome number is cut exactly in half.

Describe the monomer structure of DNA.

A nucleotide, which is composed of a deoxyribose sugar, a phosphate group, and one of four nitrogenous bases (Adenine, Thymine, Cytosine, or Guanine).

State Chargaff's Rule and explain its structural significance in DNA.

Chargaff's Rule states that in any double-stranded DNA molecule, the percentage of Adenine equals Thymine (%A = %T) and the percentage of Cytosine equals Guanine (%C = %G). This forms the basis of complementary base pairing.

Explain how semi-conservative DNA replication ensures that daughter strands relate properly to parent strands.

During replication, the two parent strands unzip. Each original parent strand serves as a template to build a brand new complementary daughter strand, resulting in two DNA molecules that each contain one old and one new strand.

Compare Transcription and Translation regarding their cellular location, biological purpose, and final product.

Transcription occurs in the nucleus to copy DNA into an mRNA strand. Translation occurs at a ribosome in the cytoplasm to read the mRNA codon sequence and build a specific protein (polypeptide).

How is an mRNA codon chart utilized during protein synthesis?

It is read in groups of three mRNA bases (codons) from the 5' to 3' direction to determine the exact sequence of amino acids that the ribosome must link together to form a protein.

Differentiate between an organism's genotype and its phenotype.

Genotype is the genetic makeup or combination of alleles (e.g., Bb), while phenotype is the physical trait or observable characteristic expressed (e.g., brown eyes).

What is the fundamental purpose of creating and analyzing a Punnett square?

To predict the mathematical probabilities of possible genotypes and phenotypes appearing in the offspring of a specific genetic cross.

Explain the difference between incomplete dominance and codominance.

In complete dominance, a heterozygous genotype results in a blended, intermediate phenotype (e.g., red and white flower making pink).

What is codominance?

Both alleles are fully and separately expressed simultaneously.

How do multiple alleles and polygenic inheritance differ?

Multiple alleles means there are more than two alternative alleles for a single gene locus, while polygenic inheritance involves multiple distinct genes controlling a single trait.

How are human ABO blood types determined genetically?

They are determined by three alleles: I^A, I^B, and i, where I^A and I^B are codominant and both are dominant over i.

How can you determine if a trait is dominant or recessive using a pedigree?

A dominant trait appears in every generation and affected individuals have at least one affected parent; a recessive trait can skip generations.

How are generations numbered on a pedigree?

Generations are designated by Roman numerals (I, II, III...) from top to bottom, and individuals within a generation are numbered left to right with Arabic numerals.

What is natural selection?

The process by which organisms with heritable traits better suited to their environment tend to survive and reproduce at higher rates.

What are the four strict requirements for natural selection?

1. Overproduction of offspring, 2. Inherited genetic variation, 3. A struggle for survival, and 4. Differential survival and reproduction.

Provide an example of natural selection.

Peppered moths changing from light to dark during the Industrial Revolution due to visibility against soot-covered trees.

Define evolution.

The change in the genetic composition of a population over successive generations.

What are four major categories of evidence supporting evolution?

Fossil record, anatomical structures, embryology, and molecular/DNA comparisons.

Approximately how old is Earth?

Earth is approximately 4.6 billion years old.

What were the defining characteristics of Earth's early atmosphere?

It was volatile, filled with volcanic gases, and lacked free oxygen.

Compare stabilizing, directional, and disruptive selection.

Stabilizing selection favors intermediate phenotypes; directional selection shifts toward one extreme; disruptive selection favors both extremes.

What are the standard taxonomic ranks?

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

What are the differences between prokaryotes and eukaryotes?

Prokaryotes lack a nucleus and membrane-bound organelles; eukaryotes have a true nucleus and complex organelles.

Which taxonomic Kingdoms can perform photosynthesis?

Plantae, Protista (algae), and Eubacteria (cyanobacteria).

Compare Archaebacteria and Eubacteria.

Both are unicellular prokaryotes; Archaebacteria lack peptidoglycan and live in extreme environments, while Eubacteria contain peptidoglycan.

Where do viruses fit into the classification system?

Viruses do not fit into the standard classification system as they are non-cellular and cannot reproduce independently.

What is a cladogram?

A branching diagram showing evolutionary relationships among species based on shared derived characteristics.

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