Biology & Earth Science JLSS Review

A comprehensive set of question-and-answer flashcards covering key Biology and Earth Science concepts from the JLSS online review notes.

What are the three main postulates of the Cell Theory?

1) All living things are composed of cells. 2) The cell is the basic unit of life. 3) All cells come from pre-existing cells.

Who are the three main proponents of the Cell Theory?

Matthias Schleiden, Theodor Schwann, and Rudolf Virchow.

Which cell type lacks a membrane-bound nucleus—prokaryotic or eukaryotic?

Prokaryotic.

Name two domains whose organisms are prokaryotic.

Bacteria and Archaea.

Give two examples of eukaryotic kingdoms.

Animals, Plants, Fungi, or Protists (any two).

Which type of cell division occurs in prokaryotes?

Binary fission.

State one size difference between prokaryotic and eukaryotic cells.

Prokaryotes are smaller (≈1–10 µm) whereas eukaryotes are larger (≈10–100 µm).

What polysaccharide composes the typical plant cell wall?

Cellulose.

Which organelle performs photosynthesis in plant cells?

Chloroplast.

Which animal-cell structure helps organize the spindle in mitosis?

Centrioles (in the centrosome).

What is the large water-filled storage structure in many plant cells called?

Central vacuole.

Rough ER vs. Smooth ER—what is the main product of each?

Rough ER synthesizes proteins; Smooth ER synthesizes lipids.

Which organelle modifies, sorts, and ships proteins?

Golgi apparatus.

Name the organelle that carries out cellular respiration to produce ATP.

Mitochondrion.

Which single-membrane organelle digests wastes and invaders?

Lysosome.

Give the function of peroxisomes.

Break down toxins and fatty acids (via oxidative reactions).

What structure provides cells with shape and internal support?

Cytoskeleton.

Which non-membrane-bound cell part assembles proteins from amino acids?

Ribosome.

Define autophagy in one phrase.

Cellular “self-eating” process that recycles damaged components via lysosomes.

State two major components of the phospholipid bilayer besides lipids.

Embedded proteins and cholesterol (carbohydrates accepted).

What property describes the cell membrane’s ability to let some substances pass but not others?

Selective permeability.

Which passive transport process moves gases like O₂ directly across the membrane?

Simple diffusion.

Facilitated diffusion requires what to move molecules across membranes?

Transport proteins (channels or carriers).

Name one active transport mechanism that engulfs large particles.

Endocytosis.

During which phase of the cell cycle is DNA replicated?

S phase of Interphase.

What are the three sub-phases of Interphase in order?

G₁, S, G₂.

Which stage of mitosis aligns chromosomes at the cell equator?

Metaphase.

In which mitotic stage do sister chromatids separate?

Anaphase.

How many daughter cells result from meiosis, and are they haploid or diploid?

Four haploid cells.

Which biomolecule class stores and transmits genetic information?

Nucleic acids (DNA & RNA).

Give one structural polysaccharide found in plants.

Cellulose (or starch for energy storage).

What principle states that allele pairs separate during gamete formation?

Law of Segregation.

Define the Law of Independent Assortment.

Genes for different traits segregate independently if on different chromosomes.

Which inheritance pattern shows a blended phenotype (e.g., red × white ⇒ pink)?

Incomplete dominance.

What do we call a tool that predicts offspring genotype ratios?

Punnett square.

DNA is composed of which four nitrogenous bases?

Adenine, Thymine, Cytosine, Guanine.

Name the enzyme that unzips DNA during replication.

Helicase.

Which enzyme adds nucleotides to a growing DNA strand?

DNA polymerase.

What is the central dogma of molecular biology?

DNA → RNA → Protein.

During translation, three-letter mRNA sequences are called what?

Codons.

Differentiate point mutation from frameshift mutation in one sentence.

Point mutation substitutes a single base, whereas frameshift adds or deletes bases, shifting the reading frame.

Write the balanced equation for photosynthesis.

6 CO₂ + 6 H₂O + sunlight → C₆H₁₂O₆ + 6 O₂.

Where in the chloroplast do light-dependent reactions occur?

Thylakoid membranes.

What are the two main outputs of the Calvin Cycle?

Glucose (or G3P) and regenerated ADP + NADP⁺.

State the overall equation for aerobic cellular respiration.

C₆H₁₂O₆ + 6 O₂ → 6 CO₂ + 6 H₂O + ATP.

Which stage of respiration produces the greatest number of ATP molecules?

Electron Transport Chain (ETC).

How many net ATP are generated during glycolysis?

Two (2) net ATP.

ATP releases energy by converting into what two products?

ADP and inorganic phosphate (Pi).

Through which plant tissues are water and minerals transported upward?

Xylem.

Name the leaf openings that regulate gas exchange in plants.

Stomata.

Which human organ system performs internal transport of nutrients and waste?

Circulatory system.

Give one plant hormone involved in growth regulation.

Auxins (others: gibberellins, abscisic acid).

Define natural selection in one sentence.

Process where individuals with advantageous traits survive and reproduce more, passing traits to offspring.

What term describes an inherited trait that increases an organism’s fitness?

Adaptation.

Name two types of evidence for evolution besides fossils.

Homologous structures, DNA similarities, or embryology (any two).

Arrange the ecological levels from smallest to largest starting with organism.

Organism → Population → Community → Ecosystem → Biosphere.

What percentage of energy is typically transferred between trophic levels?

About 10 %.

Which biogeochemical cycle involves nitrogen-fixing bacteria?

Nitrogen Cycle.

High biodiversity generally leads to what ecosystem characteristic?

Greater stability/resilience.

State the Nebular Hypothesis in one sentence.

The solar system formed from a rotating cloud of gas and dust called the solar nebula.

What is the rigid outer shell consisting of crust and upper mantle called?

Lithosphere.

Which Earth layer generates the magnetic field?

Liquid outer core.

Define plate tectonics in a phrase.

Theory describing movement of Earth’s lithospheric plates over the asthenosphere.

List four diagnostic characteristics of minerals.

Solid, naturally occurring, inorganic, crystalline structure with definite chemical composition.

On the Mohs scale, what property does hardness measure?

Resistance of a mineral to scratching.

Differentiate mineral from rock in one sentence.

A mineral is a single crystalline substance; a rock is a mixture of minerals.

Give one example each of igneous, sedimentary, and metamorphic rock.

Igneous—Basalt; Sedimentary—Sandstone; Metamorphic—Marble (any valid examples).

What two processes turn sediments into sedimentary rock?

Compaction and cementation.

Name the four major units of the Geological Time Scale from largest to smallest.

Eon → Era → Period → Epoch.

Which era followed the Mesozoic?

Cenozoic Era.

Differentiate body fossil from trace fossil with an example.

Body fossil preserves part of the organism (e.g., bone); trace fossil records activity (e.g., footprint).

What dating method uses Carbon-14 to find absolute ages?

Radiometric dating (specifically Carbon-14 dating).

Define index fossil in one sentence.

Fossil of a species that was widespread but lived for a short geologic time, useful for correlating rock layers.

List Earth’s four major systems.

Geosphere, Hydrosphere, Atmosphere, Biosphere.

Give two renewable resource examples.

Solar energy, wind energy, hydropower, forests (any two).

Why are resources unevenly distributed around the planet?

Factors such as plate tectonics, climate patterns, and ecosystem productivity cause uneven distribution.

Name one environmental impact of overfishing.

Decline in marine populations (or disruption of food webs).

Define sustainability in a single sentence.

Using resources to meet present needs without compromising future generations’ ability to meet theirs.

What process causes magma to cool into igneous rock in the rock cycle?

Cooling and solidification.

Which atmospheric layer contains most of Earth’s weather?

Troposphere (implied under Atmosphere).

What drives transpiration pull in plants?

Evaporation of water from leaf surfaces creating negative pressure.

During meiosis I, what structures separate?

Homologous chromosome pairs.

Which enzyme seals gaps between Okazaki fragments?

DNA ligase.

Give the main product of the Krebs Cycle that carries high-energy electrons to the ETC.

NADH (also FADH₂ accepted).

What cellular structure is described as a “fluid portion” where organelles float?

Cytosol.

Binary fission produces genetically offspring.

Identical.

Point mutations that do not change the encoded amino acid are called mutations.

Silent.

Which biomolecule class includes enzymes?

Proteins.

What term describes the protective outer layer present in plants but absent in animals?

Cell wall.

Name one method of active thermoregulation in animals.

Sweating, shivering, using fur/fat, vasodilation (any one).

In ecology, what organisms are called autotrophs?

Producers that make their own food via photosynthesis or chemosynthesis.

Which evolutionary process is the ultimate source of genetic variation?

Mutation.

What gas was released by volcanic activity to form Earth’s early atmosphere?

Various gases such as water vapor, CO₂, nitrogen; CO₂ is a common answer.

The densest, solid, and hottest layer of Earth is the .

Inner core.

Describe cleavage in mineralogy.

Tendency of a mineral to break along flat planes of weakness.

Which cell-cycle stage is also called the ‘resting’ phase?

G₀ phase.

What cellular process packages materials for export out of the cell?

Exocytosis.

Give an example of codominance in humans.

AB blood type (both A and B antigens expressed).

What molecule acts as the cell’s energy currency?

ATP (adenosine triphosphate).

How many chromosomes are in human somatic cells after mitosis?

46 chromosomes (diploid number).