GCSE Biology: Cells and Organisation

Comprehensive vocabulary flashcards covering GCSE Biology Topic 1 (Cell Biology) and Topic 2 (Organisation), including cell structures, transport mechanisms, cell division, the digestive system, the heart and circulatory system, and plant transport systems.

Eukaryotes

Organisms (such as animals and plants) made of cells that have a distinct nucleus containing genetic material.

Prokaryotes

Smaller and simpler organisms (such as bacteria) that do not have a nucleus; instead, they have a single circular strand of DNA and small rings of DNA called plasmids.

Plasmids

Small rings of DNA found in prokaryotic (bacterial) cells.

Subcellular Structures of Bacteria

Structures present in bacterial cells include cytoplasm, cell membrane, ribosomes, and a cell wall (not made of cellulose); they lack a nucleus, mitochondria, chloroplasts, and a permanent vacuole.

Plant Subcellular Structures

Structures found in plant cells that are absent in animal cells: a cellulose cell wall, chloroplasts, and a permanent vacuole.

Magnification Formula

$\text{Magnification} = \frac{\text{Image Size}}{\text{Real Size}}$, where image size and real size must be converted to the same unit (e.g., $\text{mm}$ to $\mu\text{m}$).

Light Microscope

A type of microscope with lower magnification (up to $\times 2{,}000$) and lower resolution ($\sim 200\,\text{nm}$), used to view living cells and large subcellular structures.

Electron Microscope

A type of microscope with higher magnification (up to $\times 2{,}000{,}000$) and much higher resolution ($0.2\text{--}10\,\text{nm}$), used to view internal cell structures in fine detail, such as ribosomes and mitochondria.

Diffusion

The net movement of particles from an area of high concentration to low concentration down a concentration gradient; a passive process that requires no energy.

Osmosis

The net movement of water molecules across a partially permeable membrane from a region of higher water potential (dilute solution) to a region of lower water potential (concentrated solution).

Active Transport

The movement of substances against the concentration gradient (from low to high concentration), requiring energy from respiration (e.g., mineral ions into root hair cells, glucose absorption in the gut).

The Cell Cycle

The process where cells grow, replicate their DNA and subcellular structures, and divide.

Mitosis

A type of cell division that produces two genetically identical diploid daughter cells used for growth, repair, and asexual reproduction.

Steps of Mitosis

1. DNA replicates to form two copies of each chromosome; 2. Chromosomes line up at the center and cell fibers pull them apart to opposite poles; 3. The cytoplasm and cell membrane divide (cytokinesis).

Cytokinesis

The final stage of cell division where the cytoplasm and cell membrane divide to form two daughter cells.

Stem Cells

Undifferentiated cells that can divide to make more stem cells or differentiate into specialized cells.

Embryonic Stem Cells

Stem cells that have the ability to differentiate into any cell type.

Adult Stem Cells

Stem cells found in bone marrow that can only turn into certain cell types (e.g., blood cells).

Plant Meristems

Tissues found in root and shoot tips that can differentiate into any plant type throughout the plant's life; used for cloning.

Hierarchy of Organisation

The structural levels of life: $\text{Cell} \rightarrow \text{Tissue} \rightarrow \text{Organ} \rightarrow \text{Organ System}$.

Tissue

A group of similar cells working together to perform a shared function (e.g., muscular tissue in the stomach).

Organ

A collection of different tissues working together to perform specific functions (e.g., the stomach contains muscle, glandular, and epithelial tissues).

Organ System

A group of organs working together to perform major life functions (e.g., the digestive system).

Enzymes

Biological catalysts that speed up chemical reactions without being used up, featuring an active site complementary to their specific substrate (Lock and Key theory).

Amylase

A digestive enzyme produced in the salivary glands, pancreas, and small intestine that breaks down starch into simple sugars.

Protease

A digestive enzyme produced in the stomach (as pepsin), pancreas, and small intestine that breaks down proteins into amino acids.

Lipase

A digestive enzyme produced in the pancreas and small intestine that breaks down lipids (fats) into glycerol and fatty acids.

Bile

A substance produced in the liver and stored in the gall bladder that neutralizes stomach acid to create the optimum pH for small intestine enzymes and emulsifies fats into tiny droplets to increase surface area for lipase action.

Benedict's Test

A food test for sugars that turns from blue to brick-red when heated.

Iodine Test

A food test for starch that changes color from orange-brown to blue-black.

Biuret Test

A food test for protein that changes color from blue to purple/lilac.

Ethanol / Sudan III Test

Food tests for lipids: Sudan III turns a red layer on top; ethanol turns cloudy white.

Double Circulatory System

A circulatory system in which the right side of the heart pumps deoxygenated blood to the lungs (pulmonary circuit) and the left side pumps oxygenated blood around the body (systemic circuit) using a thick muscular wall.

Heart Blood Pathway

$\text{Vena Cava} \rightarrow \text{Right Atrium} \rightarrow \text{Right Ventricle} \rightarrow \text{Pulmonary Artery} \rightarrow \text{Lungs} \rightarrow \text{Pulmonary Vein} \rightarrow \text{Left Atrium} \rightarrow \text{Left Ventricle} \rightarrow \text{Aorta} \rightarrow \text{Body}$.

Arteries

Blood vessels that carry blood away from the heart under high pressure; they have thick muscular and elastic walls and a narrow lumen.

Capillaries

Blood vessels with very thin walls (one cell thick) that allow the exchange of oxygen, glucose, and waste products with body cells.

Veins

Blood vessels that carry blood back to the heart under low pressure; they feature a wider lumen and valves to prevent backflow.

Plasma

The liquid component of blood carrying blood cells, nutrients, $CO_2$, hormones, and urea.

Red Blood Cells

Blood cells that contain hemoglobin to carry oxygen and do not possess a nucleus.

White Blood Cells

Cells of the immune system that engulf pathogens and produce antibodies and antitoxins.

Platelets

Small cell fragments that help blood clot at a wound.

Epidermis (Leaf)

A plant tissue covered with a waxy cuticle that helps to reduce water loss.

Palisade Mesophyll

Leaf tissue packed with chloroplasts located at the top of the leaf to absorb maximum sunlight for photosynthesis.

Spongy Mesophyll

Leaf tissue containing big air spaces to allow the diffusion of $CO_2$ and $O_2$ into and out of cells.

Stomata and Guard Cells

Tiny pores on the underside of leaves that open (to let $CO_2$ in) and close (to stop water loss), regulated by guard cells.

Xylem

Transport vessels made of dead hollow cells strengthened with lignin; transports water and mineral ions in one direction ($\text{roots} \rightarrow \text{stem} \rightarrow \text{leaves}$), driven by transpiration.

Phloem

Transport vessels made of living tube cells with sieve plates; transports dissolved sugars (glucose) in both directions via translocation.

Transpiration Rate Factors

Environmental factors that increase the rate of transpiration: increased temperature, higher airflow (wind), lower humidity, and higher light intensity.