Biology Grade 10

Nutrition

The processes organisms use to obtain and consume food (nutrients) for growth and development.

Homeostasis

The ability of an organism or cell to maintain a stable, constant internal environment.

Excretion

The removal of metabolic waste products from an organism.

Reproduction

The biological process by which organisms produce offspring.

Sensitivity (Response to Stimuli)

The ability of an organism to detect and respond to internal or external stimuli.

Prokaryotes

Single-celled organisms that lack a membrane-bound nucleus and internal membrane-bound organelles.

Eukaryotes

Cells containing a membrane-bound nucleus and specialized membrane-bound organelles.

Plant Cell

A eukaryotic cell characterized by a rigid cellulose cell wall, chloroplasts, large central vacuoles, and forming a cell plate during cytokinesis.

Animal Cell

A eukaryotic cell lacking a cell wall, dividing during cell division via a contractile ring forming a cleavage furrow.

Cell Membrane / Plasma Membrane

A semi-permeable membrane regulating the exchange of materials into and out of the cell for metabolism.

Ribosome

An organelle that synthesizes proteins by translating mRNA instructions into polypeptide chains.

Cytoplasm / Cytosol

The fluid interior of the cell where metabolic reactions occur and organelles are suspended.

DNA / RNA

Nucleic acids that store genetic instructions (DNA) or participate in protein synthesis and gene expression (RNA).

Golgi Apparatus / Body

An organelle that modifies, sorts, and packages proteins and lipids for cell transport or secretion.

Nucleus

Membrane-bound structure containing genetic material (DNA) that directs cell activity and undergoes nuclear division.

Lysosome

A membrane-bound organelle containing digestive enzymes that break down waste and cellular debris.

Mitochondrion

Organelle where cellular respiration occurs to release usable chemical energy (ATP).

Chloroplast

Organelle in plant cells where light energy is absorbed to perform photosynthesis.

Vesicle

Small membrane-bound sac used for transport within the cell and for fusing to form the cell plate in dividing plant cells.

Cell Wall

Rigid outer structural layer surrounding plant cell membranes, composed primarily of cellulose.

Endoplasmic Reticulum

Network of folded membranes involved in protein folding, lipid synthesis, and cellular transport.

Phospholipid Bilayer

A double layer of phospholipids that forms the fundamental structure of cell membranes.

Phospholipid

Membrane lipid molecule featuring a hydrophilic (water-attracting) head and hydrophobic (water-repelling) tail.

Solute

A substance dissolved inside a solvent to form a solution.

Solvent

The liquid capable of dissolving solutes (e.g., water in biological systems).

Solution

A homogeneous liquid mixture containing solutes dissolved in a solvent.

Semi-permeable

A membrane property allowing certain molecules (like water) to cross while restricting others.

Transport

The movement of molecules and substances across cell membranes or exchange surfaces.

Diffusion

The net passive movement of particles down a concentration gradient from higher to lower concentration.

Osmosis

The net movement of water molecules across a semi-permeable membrane from a region of low solute concentration to high solute concentration.

Concentration Gradient

The difference in particle concentration between two regions; steeper gradients increase transport rates.

Tonicity

The relative concentration of solutes dissolved in a solution that determines the direction of osmotic water flow.

Hypertonic

A solution with a higher solute concentration (lower water concentration) relative to the cell's interior.

Hypotonic

A solution with a lower solute concentration (higher water concentration) relative to the cell's interior.

Isotonic

A solution having an equal solute and water concentration compared to the cell cytoplasm.

Plasmolysis

Shrinkage of the cytoplasm away from the plant cell wall when placed in a hypertonic solution.

Lysis (Hemolysis)

The bursting of animal cells when placed in a hypotonic solution due to excessive osmotic water intake.

Crenation

The shriveling of red blood cells when water exits into a surrounding hypertonic solution.

Turgor Pressure

Internal pressure exerted by fluid pushing the plasma membrane against the rigid cell wall in plant cells.

Flaccid

The limp condition of a plant cell resulting from reduced turgor pressure in isotonic environments.

Interphase

The active preparatory phase of the cell cycle where metabolic reactions occur, organelles multiply, and DNA replicates.

Mitosis

Nuclear division producing two genetically identical daughter nuclei with the same diploid number of chromosomes.

Prophase

First phase of mitosis where chromatin condenses into visible chromosomes and the nuclear membrane breaks down.

Metaphase

Mitotic stage where duplicated chromosomes align along the cell's equatorial plane attached to spindle fibers.

Anaphase

Mitotic stage where spindle fibers pull sister chromatids apart at centromeres toward opposite cell poles.

Telophase

Final stage of mitosis where chromosomes reach poles and new nuclear envelopes reform around identical chromosome sets.

Cytokinesis

Division of the parent cell cytoplasm following nuclear division to yield two individual daughter cells.

Cell Cycle

The full lifespan sequence of a cell, comprising interphase, nuclear division (mitosis/meiosis), and cytokinesis.

Chromosome

Condensed structure made of DNA wrapped around proteins containing hereditary genes.

Chromatin

Uncoiled, relaxed DNA-protein complex visible during interphase and telophase.

Chromatid

One strand of a duplicated chromosome.

Sister Chromatids

Identical copies of a duplicated chromosome produced by DNA replication and held together by a centromere.

Homologous Chromosomes

Matching chromosome pairs containing identical genes at equal loci, with one inherited from each parent.

Centromere

Central region of a duplicated chromosome connecting sister chromatids and attaching to spindle fibers.

Centriole

Organelle that migrates to opposite poles during division to help organize spindle fibers.

Spindle Fibres

Protein microfilaments that attach to centromeres and contract to separate chromatids/chromosomes.

Meiosis

Reduction division producing four genetically distinct haploid gametes/nuclei from one diploid cell.

Prophase 1

Meiotic stage where homologous chromosomes align in synapsis to form bivalents and crossing over occurs.

Metaphase 1

Stage where bivalent homologous pairs line up along the cell equator via random orientation.

Anaphase 1

Stage where homologous chromosome pairs separate and move toward opposite poles.

Telophase 1

Stage where separated homologous sets arrive at poles and temporary nuclear envelopes form.

Prophase 2

Initial stage of meiosis II where nuclear envelopes break down and spindle fibers attach to individual chromosomes in haploid cells.

Metaphase 2

Stage of meiosis II where individual chromosomes align single-file along the equator.

Anaphase 2

Stage of meiosis II where sister chromatids are pulled apart toward opposite poles.

Telophase 2

Final stage of meiosis II where nuclear envelopes form around four distinct haploid nuclei.

Crossing Over

Exchange of genetic material between non-sister chromatids during prophase I, generating recombinant alleles.

Bivalent

A pair of synapsed homologous chromosomes formed during prophase I of meiosis.

Independent Assortment (Random Orientation)

The random positioning of maternal and paternal bivalents at metaphase I, creating diverse genetic combinations in gametes.

DNA (Deoxyribonucleic Acid)

Double-stranded nucleic acid containing deoxyribose sugar that encodes hereditary genetic information.

RNA (Ribonucleic Acid)

Single-stranded nucleic acid containing ribose sugar involved in gene transcription and protein translation.

Nitrogenous Bases

Nitrogen-containing base molecules forming the structural code of nucleotides.

Purine

Double-ring nitrogenous bases consisting of Adenine (A) and Guanine (G).

Pyrimidine

Single-ring nitrogenous bases consisting of Cytosine (C), Uracil (U), and Thymine (T).

Complementary Base Pairing

Specific hydrogen-bonding alignment rules between purines and pyrimidines (A-T/U and C-G).

Uracil

Pyrimidine nitrogenous base found only in RNA, pairing complementarily with Adenine.

Thymine

Pyrimidine nitrogenous base found only in DNA, pairing complementarily with Adenine.

Cytosine

Pyrimidine nitrogenous base in DNA and RNA, pairing complementarily with Guanine.

Adenine

Purine nitrogenous base in DNA and RNA, pairing complementarily with Thymine or Uracil.

Guanine

Purine nitrogenous base in DNA and RNA, pairing complementarily with Cytosine.

Gene

A specific DNA sequence that codes for a functional polypeptide or trait.

Covalent Bond

Strong chemical bond linking sugar and phosphate groups within a nucleotide chain.

Hydrogen Bonds

Weak attraction bonds holding complementary nitrogenous base pairs together across DNA strands.

Protein

A functional biological molecule composed of one or more folded polypeptide chains.

Amino Acids

The 20 fundamental organic monomer building blocks used to construct proteins.

Double Helix

The spiral arrangement of two complementary, antiparallel strands of DNA.

Phosphate Group

A structural group that forms the sugar-phosphate backbone of nucleic acids.

Pentose Sugar

A 5-carbon sugar ring component of nucleotides (ribose or deoxyribose).

Ribose

The pentose sugar component present in RNA nucleotides.

Deoxyribose

The pentose sugar component present in DNA nucleotides, lacking one oxygen atom.

Phosphodiester Bonds

Strong covalent linkages connecting pentose sugars and phosphate groups along nucleic acid backbones.

Transcription

The synthesis of RNA using a DNA template strand.

Translation

Synthesis of a polypeptide chain by ribosomes using genetic codes carried on mRNA.

Ribosomal RNA (rRNA)

Structural RNA molecules forming the core functional component of ribosomes.

Messenger RNA (mRNA)

RNA copy of a gene carrying codon sequences from DNA to ribosomes for translation.

Transfer RNA (tRNA)

Small RNA molecule carrying specific amino acids and matching anticodons to mRNA codons during translation.

RNA Polymerase

The key enzyme responsible for unwinding DNA and transcribing an RNA strand.

Codon

A three-nucleotide sequence on mRNA coding for a specific amino acid or stop signal.

Anticodon

A three-base sequence on tRNA complementary to a specific mRNA codon.

Allele

Alternative forms or genetic variants of a specific gene.