Comprehensive Science Review: Genetics, Environmental Science, Chemistry, and Physics

Flashcards providing comprehensive question-and-answer review across Genetics, Environmental Science, Chemistry, and Physics based on the study guide transcript.

What are the main organelle structures found within a eukaryotic cell and what do they do?

Key organelles include the nucleus (stores genetic DNA and directs cellular activities), mitochondria (site of cellular respiration producing ATP energy), ribosomes (synthesize proteins), endoplasmic reticulum (modifies and transports proteins and lipids), Golgi apparatus (packages and distributes proteins), and the cell membrane (controls the movement of substances in and out of the cell).

What are the main similarities and differences between animal, plant, and fungal cells?

All three cell types are eukaryotic, containing a membrane-bound nucleus and organelles such as mitochondria. Plant cells have a cellulose cell wall, large central vacuole, and chloroplasts for photosynthesis. Fungal cells have a cell wall made of chitin and lack chloroplasts. Animal cells lack a cell wall and chloroplasts entirely.

What are DNA and RNA, and what are the primary differences between them?

DNA (deoxyribonucleic acid) stores genetic instructions and has a double-helix structure with deoxyribose sugar and bases A, T, C, G. RNA (ribonucleic acid) is typically single-stranded, contains ribose sugar, functions in protein synthesis, and replaces thymine ($\text{T}$) with uracil ($\text{U}$).

What is a chromosome, and what is an allele?

A chromosome is a thread-like structure of packaged DNA and proteins located in the nucleus that carries genetic information. An allele is an alternative or variant form of a specific gene.

What is the difference between transcription and translation?

Transcription is the process in the nucleus where a specific segment of DNA is transcribed into messenger RNA ($\text{mRNA}$). Translation is the process at the ribosome in the cytoplasm where the $\text{mRNA}$ sequence is decoded to build a chain of amino acids into a functional protein.

What is a codon, and what does it code for?

A codon is a three-nucleotide sequence on an $\text{mRNA}$ strand that codes for a specific amino acid or acts as a start or stop signal during protein synthesis.

What is the complementary DNA sequence to the strand ATA CCG CAT ATG?

The complementary DNA sequence is TAT GGC GTA TAC (base pairing Adenine with Thymine and Cytosine with Guanine).

What is the RNA sequence transcribed from the DNA sequence ATA CCG CAT ATG, and which nucleotide is replaced?

The RNA sequence is UAU GGC GUA UAC. In RNA, uracil ($\text{U}$) replaces thymine ($\text{T}$) to pair with adenine ($\text{A}$).

What is mitosis, what are its 4 main functions, and does it produce haploid or diploid cells?

Mitosis is a process of nuclear division producing two genetically identical diploid cells ($2n$). Its four main functions are organismal growth, tissue repair, cell replacement, and asexual reproduction.

What is meiosis, what is its main function, and does it produce haploid or diploid cells?

Meiosis is a specialized form of cell division that reduces the chromosome number by half to produce four genetically diverse haploid cells ($n$). Its main function is the production of gametes (sperm and egg cells) for sexual reproduction.

What is a trisomy disorder, and what is an example of one?

A trisomy disorder occurs when a cell has three copies of a particular chromosome instead of the normal two. A common example is Down syndrome, also known as Trisomy 21.

What is the difference between a genotype and a phenotype?

Genotype refers to the specific genetic makeup or combination of alleles of an organism (e.g., $Hh$ or $hh$). Phenotype refers to the observable physical traits or characteristics expressed by the genotype (e.g., brown eyes or blue eyes).

What do the terms homozygous dominant, heterozygous, and homozygous recessive mean?

Homozygous dominant means having two dominant alleles (e.g., $HH$). Heterozygous means having one dominant and one recessive allele (e.g., $Hh$). Homozygous recessive means having two recessive alleles (e.g., $hh$).

How is the trait genotype Hh classified?

It is classified as heterozygous (or hybrid), because it contains two different alleles for the same trait.

What are the resulting offspring genotypes and probabilities for a cross between parents with genotypes Hh and hh?

A cross of $Hh \times hh$ yields a $50\%$ ($2/4$) probability of heterozygous ($Hh$) offspring and a $50\%$ ($2/4$) probability of homozygous recessive ($hh$) offspring.

In a pedigree chart, what do a circle, a square, and a shaded-in symbol represent?

A circle represents a female, a square represents a male, and a shaded-in symbol indicates an individual who expresses or is affected by the genetic trait being tracked.

What is evolution, and what is the difference between convergent and divergent evolution?

Evolution is the change in heritable traits of biological populations over generations. Divergent evolution occurs when related species evolve different adaptations from a common ancestor (e.g., Darwin's finches). Convergent evolution occurs when unrelated species independently evolve similar traits due to adapting to similar environments (e.g., dolphins and sharks).

What is natural selection, and who formulated this theory?

Natural selection, formulated by Charles Darwin, is the mechanism of evolution where organisms with favorable variations better suited to their environment are more likely to survive and reproduce, passing those traits to the next generation (e.g., peppered moths adapting to industrial soot).

What are fossils, living fossils, and transitional fossils?

Fossils are preserved remains or impressions of ancient organisms. A living fossil is an extant species that closely resembles ancient forms and has remained largely unchanged over geological time (e.g., the coelacanth). A transitional fossil exhibits traits common to both an ancestral group and its derived descendant group (e.g., Archaeopteryx).

What are the four main spheres of Earth?

The four main spheres are the atmosphere (air and gases), hydrosphere (all water bodies), lithosphere or geosphere (crust and solid rock), and biosphere (all living organisms).

What is the water cycle?

The continuous movement of water on, above, and below the surface of the Earth, driven by solar energy and gravity through processes including evaporation, transpiration, condensation, precipitation, and runoff.

What is an ecosystem, and what are key requirements a living organism needs in a habitat?

An ecosystem is a biological community of interacting organisms and their physical abiotic environment. In a habitat, living things require water, food/nutrients, shelter, air/oxygen, suitable temperature, space, and a mate for reproduction.

What are the four main groups of animals classified by their diet?

Herbivores (eat plants), carnivores (eat other animals), omnivores (eat both plants and animals), and detritivores or decomposers (feed on dead organic matter).

What is the difference between a food chain and a food web, and what happens if a species is removed?

A food chain shows a single linear pathway of energy flow from producer to consumer. A food web consists of interconnected food chains in an ecosystem. Removing a species disrupts the balance, potentially causing overpopulation of its prey and food shortages for its predators (trophic cascade).

What is an apex predator, and what is an introduced species?

An apex predator is a predator at the top of a food chain that has no natural predators in its ecosystem (e.g., great white shark, lion). An introduced species is a non-native organism transported by human activity into a new ecological region (e.g., cane toad in Australia).

What is a predator-prey relationship?

An interaction where one organism (the predator) hunts, captures, and feeds on another organism (the prey), resulting in linked population cycles where predator numbers typically fluctuate in response to prey abundance.

What are the three main symbiotic relationships found in an ecosystem?

Mutualism: both species benefit (e.g., bees and flowering plants). Commensalism: one species benefits while the other is unaffected (e.g., barnacles on whales). Parasitism: one species benefits at the expense of harming the host (e.g., ticks on dogs).

How are climate change and global warming similar, and how are they different?

Both refer to large-scale changes in Earth's climate driven by greenhouse gases. Global warming refers specifically to the long-term increase in Earth's average surface temperature, while climate change is a broader term encompassing global warming as well as shifting precipitation patterns, rising sea levels, and increased extreme weather events.

How do human activities influence climate change?

Human activities emit excess greenhouse gases (like $CO_2$ and $CH_4$) through the burning of fossil fuels for energy and transport, deforestation which reduces carbon sinks, industrial agriculture, and landfill waste, trapping heat in the atmosphere.

In the periodic table, what do groups and periods refer to?

Groups are vertical columns containing elements with the same number of valence electrons and similar chemical properties. Periods are horizontal rows indicating the number of electron shells an atom has.

What are the three main parts of an atom, including their charges and positions?

Protons have a positive charge ($+1$) and are located in the central nucleus. Neutrons have no charge ($0$) and are located in the nucleus. Electrons have a negative charge ($-1$) and orbit the nucleus in electron shells.

What do the atomic number and atomic mass tell you about an element?

The atomic number indicates the number of protons in the nucleus of an atom (which defines the element). The atomic mass indicates the total mass of the atom, which approximately equals the number of protons plus neutrons.

How many electrons fit into the 1st, 2nd, and 3rd electron shells, and what is the electron configuration for Neon?

The 1st shell holds up to $2$ electrons, the 2nd holds up to $8$, and the 3rd holds up to $8$ (for elements up to calcium). Neon (atomic number $10$) has an electron shell configuration of $2, 8$.

What is a physical change, and what are 5 observations indicating one has occurred?

A physical change alters the form or state of matter without changing its chemical composition. Five observations include change in state (e.g., melting or boiling), change in shape, change in size, dissolving of a solute, and deformation (e.g., bending or tearing).

What is a chemical change, and what are up to 5 observations indicating one has taken place?

A chemical change forms one or more new substances with different properties. Five observations include an unexpected color change, a temperature change (heat absorbed or released), the production of a gas (bubbles/odor), the formation of a solid precipitate, and the emission of light.

What are elements and compounds, and do compounds behave the same way as their constituent elements?

An element is a pure substance made of only one type of atom. A compound is a substance formed from two or more different elements chemically bonded together. Compounds do not behave like their individual elements; they possess entirely distinct physical and chemical properties.

In a chemical equation, what are reactants and products?

Reactants are the starting substances found on the left side of the reaction arrow that undergo chemical change. Products are the newly formed substances found on the right side of the arrow.

What are the four common types of chemical reactions: synthesis, decomposition, single/double replacement, and combustion?

Synthesis combines reactants to form one product ($A + B \rightarrow AB$). Decomposition breaks one compound into multiple products ($AB \rightarrow A + B$). Single replacement swaps one element in a compound ($A + BC \rightarrow AC + B$). Double replacement exchanges ions between two compounds ($AB + CD \rightarrow AD + CB$). Combustion is a reaction with oxygen releasing heat and light.

What is combustion, and what are the products of a complete hydrocarbon combustion reaction?

Combustion is a high-temperature exothermic reaction where a fuel reacts with oxygen. The products of complete combustion of a hydrocarbon are carbon dioxide ($CO_2$) and water ($H_2O$).

What is the balanced chemical equation for the reaction where hydrogen is combined with oxygen to make water?

$$2H_2 + O_2 \rightarrow 2H_2O$$

What is the balanced chemical equation for hydrochloric acid reacting with magnesium to produce magnesium chloride and hydrogen gas?

$$Mg + 2HCl \rightarrow MgCl_2 + H_2$$

What is the balanced chemical equation for the combustion of glucose (sugar) with oxygen?

$$C_6H_{12}O_6 + 6O_2 \rightarrow 6CO_2 + 6H_2O$$

What is a catalyst, and what are common examples?

A catalyst is a substance that increases the rate of a chemical reaction by lowering the activation energy without being consumed in the reaction. Examples include biological enzymes (such as catalase and amylase) and metal catalysts like platinum or nickel.

What is a precipitation reaction?

A chemical reaction in an aqueous solution where two soluble ionic salts react to form an insoluble solid product called a precipitate.

What is the difference between speed and velocity, and which is scalar versus vector?

Speed is a scalar quantity measuring the rate at which an object covers distance ($\text{distance}/\text{time}$) without direction. Velocity is a vector quantity that specifies both the speed and the direction of an object's motion ($\text{displacement}/\text{time}$).

What is the difference between distance and displacement?

Distance is a scalar quantity representing the total path length traveled by an object. Displacement is a vector quantity representing the shortest straight-line distance and direction from an object's initial position to its final position.

What are the formulas for average speed and average velocity?

The formula for average speed is $s = \frac{d}{t}$ (distance divided by time). The formula for average velocity is $v = \frac{\Delta x}{t}$ (displacement divided by time).

What is acceleration, what is its formula, and how is it related to velocity?

Acceleration is the rate of change of velocity over time. Its formula is $a = \frac{\Delta v}{t} = \frac{v - u}{t}$, where $v$ is final velocity, $u$ is initial velocity, and $t$ is time. An object accelerates whenever its speed increases, decreases, or changes direction.

What is a force, and what are common examples?

A force is a push or pull exerted on an object resulting from its interaction with another object. Examples include gravity, friction, normal force, tension, and applied force.

What are Newton's three laws of motion, and which law relates to inertia?

Newton's First Law (Law of Inertia) states an object remains at rest or in constant uniform motion unless acted upon by a net external force. Newton's Second Law states that force equals mass times acceleration ($F = ma$). Newton's Third Law states that for every action, there is an equal and opposite reaction. Inertia relates to the First Law.

Using Newton's Second Law, what is the force of an object with a mass of 50 kg accelerating at 40 m/s²?

Using $F = ma$: $F = 50\,\text{kg} \times 40\,\text{m/s}^2 = 2000\,\text{N}$.

Using Newton's Second Law, what is the mass of an object when an applied force is 100 N and its acceleration is 25 m/s²?

Using $m = \frac{F}{a}$: $m = \frac{100\,\text{N}}{25\,\text{m/s}^2} = 4\,\text{kg}$.

Using Newton's Second Law, what is the acceleration of an object when a force of 2000 N is applied to a mass of 500 kg?

Using $a = \frac{F}{m}$: $a = \frac{2000\,\text{N}}{500\,\text{kg}} = 4\,\text{m/s}^2$.

What is an example of an action-reaction force pair illustrating Newton's Third Law?

When a swimmer pushes backward on the water with their hands (action force), the water pushes forward on the swimmer with an equal and opposite force (reaction force), propelling the swimmer forward.

Due to inertia, what direction will a stationary ball in a car roll if the car suddenly brakes, accelerates, or turns?

When the car suddenly brakes, the ball rolls forward; when the car accelerates forward, the ball rolls backward; when the car turns left, the ball rolls right; and when the car turns right, the ball rolls left.

What is energy, and what are its different forms?

Energy is the capacity to do work. Forms of energy include kinetic energy, potential energy (gravitational, elastic, and chemical), thermal energy, electrical energy, radiant/light energy, sound energy, and nuclear energy.

What is the Law of Conservation of Energy?

The Law of Conservation of Energy states that energy cannot be created or destroyed; it can only be transformed from one form to another, meaning the total energy in an isolated system remains constant.