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Quizzes > Science

Easy biology questions: test your knowledge of cells, DNA, and ecosystems

Quick quiz of biology questions with answers. Instant results.

Editorial: Review CompletedCreated By: Michael DobreskiUpdated Aug 24, 2025
Difficulty: Moderate
2-5mins
Learning OutcomesCheat Sheet
Paper art illustration for Biology Questions Quiz featuring cells, DNA, ecosystems on teal background

Use this biology questions quiz to check your grasp of cells, DNA, and ecosystems. Answer a mix of simple and tricky items, get your score, and spot what to review next. For more practice, try our biology knowledge quiz, a biology true or false quiz, or a biology chapter 1 practice test.

The "powerhouse" of the cell, which generates most of the cell's ATP, is known as the:
Mitochondrion
Golgi apparatus
Nucleus
Ribosome
Mitochondria are double-membrane organelles that produce ATP through oxidative phosphorylation. They contain their own DNA and are central to energy metabolism in eukaryotic cells. Dysfunction in mitochondria can lead to metabolic disorders and reduced ATP generation. .
What molecule carries the genetic instructions used in growth, development, and functioning of almost all living organisms?
Protein
ATP
RNA
DNA
DNA (deoxyribonucleic acid) stores hereditary information in the sequence of its nucleotide bases. It is replicated and transmitted to daughter cells during cell division. Genes, segments of DNA, code for proteins that carry out cellular functions. .
Photosynthesis occurs in which organelle of plant cells?
Chloroplast
Lysosome
Endoplasmic reticulum
Mitochondrion
Chloroplasts contain chlorophyll and capture light energy to convert carbon dioxide and water into glucose and oxygen. They evolved from endosymbiotic cyanobacteria. Chloroplasts are found only in plants and some protists. .
What is the fundamental unit of life that contains genetic material and performs metabolic processes?
Molecule
Cell
Atom
Organ
The cell is the smallest unit of life capable of performing all life processes. It contains organelles such as the nucleus, mitochondria, and ribosomes to sustain metabolism. Cells reproduce and respond to their environment. .
Which type of bond is responsible for the cohesive properties of water by connecting individual H?O molecules?
Covalent bond
Hydrogen bond
Peptide bond
Ionic bond
Hydrogen bonds form between the slightly positive hydrogen atom of one water molecule and the slightly negative oxygen atom of another. They give water high cohesion, surface tension, and a high heat capacity. These properties are vital for biological systems. .
According to the endosymbiotic theory, which organelle originated from free-living bacteria?
Nucleus
Endoplasmic reticulum
Chloroplast
Mitochondrion
The endosymbiotic theory proposes that mitochondria were once free-living proteobacteria that entered into a symbiotic relationship with ancestral eukaryotic cells. Evidence includes their own circular DNA and double membranes. This acquisition enabled efficient aerobic respiration. .
During DNA replication, which enzyme unwinds the double helix by breaking hydrogen bonds between base pairs?
Primase
Helicase
DNA polymerase
Ligase
Helicase separates the two strands of the DNA double helix ahead of the replication fork by breaking hydrogen bonds between base pairs. This unwinding is essential for polymerases to access each strand. Mutations in helicase can lead to replication errors. .
In protein synthesis, transfer RNA (tRNA) anticodons pair with what on the messenger RNA?
Codons
Introns
Exons
Ribosome sites
tRNA molecules have an anticodon triplet that base-pairs with the complementary mRNA codon during translation. This ensures that the correct amino acid is added to the growing polypeptide chain. The ribosome facilitates this codon-anticodon pairing. .
Which metabolic process regenerates NAD? under anaerobic conditions in muscle cells?
Aerobic respiration
Beta-oxidation
Fermentation
Photophosphorylation
Lactic acid fermentation in muscle cells converts pyruvate to lactate and regenerates NAD?, allowing glycolysis to continue in the absence of oxygen. This process temporarily supplies ATP during intense exercise. Accumulation of lactate can lead to muscle fatigue. .
Which tissue type primarily provides structural support by producing extracellular matrix?
Epithelial tissue
Connective tissue
Nervous tissue
Muscle tissue
Connective tissue cells secrete fibers and ground substance to form the extracellular matrix, providing support and structure to organs. Examples include bone, cartilage, adipose tissue, and blood. They also play roles in nutrient transport and immune response. .
The G1 checkpoint in the cell cycle primarily assesses which of the following before DNA replication?
DNA damage
Spindle fiber attachment
Chromosome segregation
Cytokinesis
The G1 checkpoint evaluates DNA integrity and the cell's size and nutrient status before committing to DNA synthesis. If damage is detected, the cell can repair DNA or enter apoptosis. Proper checkpoint function prevents propagation of mutations. .
In the lac operon of E. coli, what molecule acts as the inducer by binding to the repressor and allowing transcription?
Lactose
Allolactose
Glucose
cAMP
Allolactose, an isomer of lactose, binds to the lac repressor, causing it to release from the operator sequence and permit transcription. This induction allows enzymes for lactose metabolism to be expressed when lactose is present. .
Which epigenetic modification involves adding methyl groups to cytosine bases in DNA, often leading to gene silencing?
Phosphorylation
Hydroxylation
Methylation
Acetylation
DNA methylation usually occurs at CpG sites where DNA methyltransferases add methyl groups to cytosine. This modification can repress transcription by preventing transcription factor binding or recruiting repressive proteins. It plays a role in development and disease. .
In vascular plants, which tissue transports sugars produced in the leaves to other parts of the plant?
Phloem
Xylem
Cambium
Mesophyll
Phloem consists of sieve tube elements and companion cells that conduct sugars (primarily sucrose) from sources (like leaves) to sinks (roots, growing tissues). This process, called translocation, relies on pressure-flow dynamics. Xylem, by contrast, moves water and minerals. .
Which equation describes the relationship between allele and genotype frequencies under Hardy - Weinberg equilibrium?
2p + q = 1
p + q = 1
p^2 + 2pq + q^2 = 1
p^2 - q^2 = 1
Under Hardy - Weinberg equilibrium, allele frequencies p and q relate to genotype frequencies as p^2 (homozygous dominant) + 2pq (heterozygous) + q^2 (homozygous recessive) = 1. This model assumes random mating and no evolutionary forces. It serves as a null hypothesis in population genetics. .
The CRISPR-Cas9 system uses which molecule to guide the Cas9 enzyme to a specific DNA sequence for targeted editing?
Ribosomal RNA
Guide RNA
Primer DNA
Restriction enzyme
Guide RNA (gRNA) in CRISPR-Cas9 is engineered to complement a target DNA sequence, directing Cas9 to induce a double-strand break at that locus. This specificity enables gene knockout or insertion in genome editing. The mechanism has revolutionized biotechnology and medicine. .
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Study Outcomes

  1. Identify Cell Structures -

    After completing the quiz, learners will be able to recognize major cell components and recall their functions, reinforcing key concepts in biology questions.

  2. Explain DNA Structure and Role -

    Participants will describe the double”helix architecture of DNA and understand how it governs heredity, preparing them for more advanced biology test topics.

  3. Classify Ecosystem Interactions -

    Users will differentiate producers, consumers, and decomposers within ecosystems, applying their knowledge to question related to biology in real”world contexts.

  4. Apply Strategies to Answer Biology Test Questions -

    Quiz takers will use effective tactics for tackling multiple”choice items, boosting confidence when facing easy biology questions or more challenging prompts.

  5. Utilize Biology Questions and Answers for Self-Assessment -

    With immediate scoring and explanations, learners will pinpoint areas for improvement and track their progress, making review sessions more focused and productive.

Cheat Sheet

  1. Cell Structure & Function -

    Key organelles like the nucleus, mitochondria and endoplasmic reticulum coordinate DNA storage, energy production, and protein synthesis. The fluid mosaic model - imagine a sea of lipids with floating protein "icebergs" - explains membrane dynamics. Remember higher to lower concentration for passive transport and active transport moves against gradients using ATP.

  2. DNA Structure & Replication -

    DNA's double helix relies on complementary base pairing (A-T and G-C) to encode genetic information. Replication is semiconservative: each new DNA molecule retains one original strand, guided by enzymes like DNA polymerase. Mnemonic "Apple Trees Grow Constantly" helps recall A-T and G-C pairings when tackling biology questions.

  3. Photosynthesis & Cellular Respiration -

    Photosynthesis converts light energy into glucose: 6 CO2 + 6 H2O → C6H12O6 + 6 O2, while cellular respiration reverses this to release ATP. Understanding both pathways clarifies energy flow in cells and ecosystems. A quick trick: "Photo makes sugar; 'cyto' eats sugar" to keep the reactions straight.

  4. Mendelian Genetics & Punnett Squares -

    Gregor Mendel's pea experiments revealed dominant vs recessive inheritance and the 3:1 ratio in monohybrid crosses. Use Punnett squares to predict genotypic and phenotypic ratios - key for multiple choice biology tests. Think "3 tall, 1 short" and apply dihybrid 9:3:3:1 ratios when exploring linked vs independent assortment.

  5. Ecosystem Levels & Energy Flow -

    Ecology questions often ask for trophic levels: producers, primary consumers, secondary consumers, and decomposers, with only ~10% energy transfer each step. Remember the acronym "OPPER" for Organism, Population, Community, Ecosystem, and Biome, then Biosphere. Visualizing food webs boosts your confidence on any biology test covering ecosystems.

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