biology Flashcards
Prokaryotic Cells
Definition: Unicellular organisms that lack membrane-bound organelles.
Characteristics: Small and simple cells, large surface area to volume (SA
) ratio, optimal nutrient intake.
Examples: Bacteria and archaea.
Eukaryotic Cells
Definition: Uni- or multicellular organisms with membrane-bound organelles.
Characteristics: Large and complex cells, small SA
ratio, DNA is compartmentalized in a nucleus.
Examples: Plants, animals, fungi, protists.
Prokaryotic Cell Features
Cell (plasma) membrane: Controls entry and exit of substances.
Plasmids: Small rings containing genetic material.
Cell wall: Provides protection and structural support.
Pili: Hair-like structures for adherence.
Flagella: Tails for locomotion.
Capsule: Layer of complex carbohydrates for protection.
Eukaryotic Cell Organelles
Nucleus: Headquarters of the cell, stores DNA.
Mitochondria: Powerhouse of the cell, generates energy.
Ribosomes: Manufacture proteins.
Chloroplasts: Carry out photosynthesis in plant cells.
Golgi apparatus: Prepares and packages proteins for use or export.
Endoplasmic Reticulum (ER): Rough ER ships materials, smooth ER makes lipid
Cell Theory
All organisms are made of cells.
All new cells arise from pre-existing cells.
The cell is the smallest unit of life.
Characteristics of Life
Growth and change.
Responsiveness to the environment.
Reproduction and inheritance of traits.
Metabolism and homeostasis.
Cellular composition.
Microscopes
Light microscope: Magnification up to 2000x, can view living and non-living specimens.
Fluorescent microscope: Uses fluorescent markers to target specific structures.
Electron microscope (TEM & SEM): High magnification, only views non-living specimens.
Confocal laser scanning microscope: Creates 3D models by combining layers of images.
Membrane Proteins
Transport: Facilitates diffusion/active transport.
Receptor: Receives signals from other cells or hormones.
Recognition: Cellular ID markers.
Adhesion: Interactions between cells/extracellular matrix.
Photosynthesis Stages
Light-dependent stage: Splits water molecules, produces oxygen, hydrogen ions, and ATP.
Light-independent stage: Uses carbon dioxide and hydrogen to produce glucose.
Cell Functions
Diffusion: Movement from high to low concentration.
Osmosis: Water moves from low solute concentration to high solute concentration across a semipermeable membrane.
Active transport: Moves molecules from low to high concentration, requires energy.
Enzymes
Function: Biological catalysts that lower activation energy.
Factors affecting activity: Temperature, pH level, and substrate concentration.
Magnification Levels:
10x (ocular lens) × 4x (objective lens) = 40x (low magnification)
10x (ocular lens) × 10x (objective lens) = 100x (high magnification)
10x (ocular lens) × 40x (objective lens) = 400x (high magnification)
Cytoplasm
Semi-liquid environment that suspends organelles
Nucleus
Function: Control center of the cell; houses DNA.
Chloroplasts
Location: Only in plant cells.
Function: Site of photosynthesis.
Ribosomes
Function: Protein synthesis; composed of RNA and proteins
Mitochondria
Function: Energy production through cellular respiration.
Golgi Apparatus
Function: Modifies, sorts, and packages proteins for secretion.
Endoplasmic Reticulum (ER):
Rough ER: Synthesizes proteins.
Smooth ER: Synthesizes lipids, detoxifies chemicals, and stores calcium
Lysosomes
Function: Contain digestive enzymes to break down waste materials.
Vacuoles
Function: Storage of nutrients, water, and waste
Cell Membrane
Function: Controls the movement of substances in and out of the cell; selectively permeable
Membrane Structure: Fluid Mosaic Model
Phospholipid Bilayer: Composed of hydrophilic heads and hydrophobic tails.
Cholesterol: Stabilizes the membrane, making it less permeable to water-soluble substances.
Proteins:
Channel Proteins: Facilitate passive transport of molecules.
Carrier Proteins: Facilitate active transport.
Transport Mechanisms
Diffusion:
Definition: Movement of molecules from high to low concentration.
Driven By: Concentration gradient.
Osmosis:
Definition: Movement of water across a semipermeable membrane from low solute concentration to high solute concentration.
Active Transport:
Definition: Movement of molecules against the concentration gradient.
Requires: Energy (ATP) and carrier proteins.
Endocytosis:
Definition: Process by which the cell engulfs material into a vesicle.
Types:
Phagocytosis: Engulfment of solid particles.
Pinocytosis: Engulfment of liquid.
Exocytosis
Definition: The process of expelling materials from the cell via vesicles.
Examples: Release of enzymes, antibodies, and waste.
Organic Compounds:
Carbohydrates: Serve as energy sources and structural components (e.g., glucose, starch).
Lipids: Energy storage molecules with hydrophobic properties (e.g., fats, oils).
Proteins: Structural and functional roles (e.g., enzymes, hemoglobin).
Nucleic Acids: DNA and RNA, which carry genetic information and assist in protein synthesis.
Inorganic Compounds
Water: Universal solvent, essential for biochemical reactions.
Minerals: Important for cellular processes (e.g., sodium, calcium).
Gases: Involved in respiration and photosynthesis (e.g., oxygen, carbon dioxide).
Light-Dependent photosynthesis
Location: Chloroplast (thylakoid membrane).
Function: Splits water into oxygen, hydrogen ions, and electrons. Produces ATP.
Light-Independent photosynthesis (calvin cycle)
Location: Chloroplast (stroma).
Function: Uses carbon dioxide and hydrogen to produce glucose. ATP from the light-dependent stage powers this reaction.
Cellular Waste Removal
Oxygen and Carbon Dioxide: Removed via diffusion.
Excess Water: Removed by osmosis.
Waste from Protein Breakdown: Exits through diffusion or exocytosis.
Factors Affecting Enzyme Activity
Temperature: Optimal temperature needed for maximum activity.
pH Level: Enzymes work best in specific pH ranges.
Substrate Concentration: Enzyme activity increases with more substrate until saturation occurs.
Unicellular Organisms
Definition: Single-celled organisms, either prokaryotic or eukaryotic.
Examples: Paramecium, bacteria.
Functionality: One cell performs all life processes.
Colonial Organisms
Definition: Group of identical single-celled organisms forming colonies.
Functionality: Each cell can independently perform life processes, yet they work together.
Multicellular Organisms
Definition: Composed of many different types of cells that specialize to perform specific functions.
Dependency: Cells cannot function independently
Cell Specialization and Differentiation
Order: Cells → Tissues → Organs → Systems.
Specialization: Cells are specialized to perform distinct functions within tissues and organs.
Plant Systems and Tissues
Shoot System:
Function: Provides structural support and a transport pathway between roots and leaves.
Root System:
Function: Anchors the plant, absorbs water via osmosis, and nutrients via active transport.
Types of Plant Tissue:
Dermal Tissue:
Function: Acts as the skin of the plant for protection.
Ground Tissue:
Function: Fills the space between vascular and dermal tissue.
Vascular Tissue:
Xylem: Transports water and minerals from roots to leaves.
Phloem: Transports sugars (sap) from leaves to other parts of the plant.
Xylem
Transports water and minerals from roots to leaves.
Phloem
Transports sugars (sap) from leaves to other parts of the plant.
Stomata
Function: Regulate gas exchange and control water loss by adjusting the size of the stomatal pore.
Environmental Triggers: Humidity, CO₂ concentration, light intensity.
Cycle: Opens during the day, closes at night.
Xylem
Function: Transports water and dissolved minerals from roots to leaves.
Components:
Tracheids: Water and ions pass through small holes (pits) between tracheids.
Xylem Vessels: Hollow tubes formed from dead cells for water transport.
Phloem
Function: Transports sugars (products of photosynthesis) from leaves to the rest of the plant.
Components:
Sieve Tube Cells: Create channels for sugar transport.
Companion Cells: Support sieve tube cells (function unclear).
Translocation: Movement of sugars from regions of high pressure (near production) to low pressure (where sugars are used/stored).
Open Circulatory System
Function: Blood (hemolymph) bathes organs directly in an open cavity.
Examples: Invertebrates like insects and spiders.
Key Features:
One or more hearts.
Open-ended vessels return blood to the heart.
Closed Circulatory System
Function: Blood circulates within a network of blood vessels.
Examples: Vertebrates like fish, frogs, and mammals.
Key Features:
Heart pumps blood through sealed arteries and veins.
Arteries withstand high pressure due to their thick elastic walls.
Cardiovascular System
Type: Closed circulatory system.
Function: Uses blood to transport oxygen, nutrients, and waste throughout the body.
Lymphatic System
Type: Open circulatory system.
Function: Circulates lymph fluid, helping maintain osmotic balance and immune defense.
Selection Pressure in an Ecosystem
Biotic Factors (Living Components)
Seasonal availability and abundance of food.
Number of competitors, mates, and predators.
Variety of disease-causing organisms.
Selection Pressure in an Ecosystem Abiotic Factors (Non-Living Components)
Temperature (affects enzymes in cells).
Light availability, water availability.
Availability of gases (oxygen, carbon dioxide).
Soil type, exposure to natural forces (wind, tides, waves).
Structural Adaptations
Changes in the shape or size of body parts.
Example: Kangaroo’s powerful legs help it hop quickly.
Physiological Adaptations:
Relate to how an organism functions.
Example: Human sweating helps with heat loss.
Behavioral Adaptations
Relate to how an organism responds to its environment.
Example: Penguins huddle together to stay warm.
Darwin’s Theory of Evolution by Natural Selection
Variation: In any population, individuals vary.
Survival of the Fittest: Individuals with favorable adaptations survive and reproduce.
Passing Traits: Favorable traits are passed to offspring.
Evolution Over Time: Favorable traits become more common in the population.
Genetic Diversity
The total number of genetic characteristics in a species’ genetic makeup, influenced by selection pressures.
Species Diversity
The variety of different species in an ecological community
Ecosystem Diversity
The variety of ecosystems found in a region.
Key Terms of Evolution
Microevolution:
Small evolutionary changes within a population, such as changes in gene frequency over a short time.
Example: Evolution of horses.
Key Terms of Evolution
Speciation
The formation of new species due to factors like geographical isolation.
Key Terms of Evolution Macroevolution:
Large-scale evolutionary changes that occur over millions of years, resulting in new species.
Example: Fossil records of horses’ leg bones and teeth.
Evolutionary Patterns
Divergent Evolution:
Species evolve from a common ancestor but diverge into different forms due to environmental pressures.
Isolation is key to the formation of distinct species.
Evolutionary Patterns Convergent Evolution:
Unrelated species develop similar traits due to similar environmental pressures.
Example: Dolphins (mammal), sharks (fish), and penguins (bird) all have streamlined bodies for aquatic environments.
Evolutionary Patterns Punctuated Equilibrium
Evolution occurs in bursts of rapid change, followed by long periods of stability.
Evolutionary Patterns Gradualism
Evolutionary changes occur gradually over a long time, as originally proposed by Darwin.
Biochemical Evidence for Evolution
Advantages:
Allows for quantitative comparisons between organisms.
Provides detailed information, particularly through DNA analysis.
Biochemical Evidence for Evolution
disadvantages:
Techniques are complex and expensive.
DNA provides the most detailed but resource-intensive information.
Habitat
The place where an organism lives
Population
All members of a species living in a particular habitat.
Community
Different species populations living in the same place at the same time.
Niche
The role an organism plays within its environment
Ecosystem
A combination of all the biotic (living) and abiotic (non-living) features in an area.
Dynamic: Continuously influenced by changing populations and physical environments.
Logistic Model of Population Growth
Initial Stage:
Slow growth due to a small population and low offspring numbers.
Exponential Growth:
Population grows rapidly as birth and immigration exceed death and emigration.
Limiting Factors:
Density-dependent factors (disease, competition, predation) slow growth. Resources become scarce as population grows.
Carrying Capacity:
Population reaches a stable maximum that the environment can support. Growth plateaus.
Intraspecific Competition
Competition within a species for mates, food, and shelter
Interspecific Competition
Competition between species for resources, leading to survival advantages or adaptations.
Short-Term Impact: Winner’s population increases, loser’s decreases.
Long-Term Impact: Can lead to environmental degradation, reduced biodiversity, and possibly extinction.
Mutualism
Both species benefit.
Example: Clownfish and sea anemone (protection for the fish, cleaning for the anemone).
Commensalism
One species benefits, while the other is neither harmed nor helped.
Example: A bird nesting in a tree
Parasitism
One organism (parasite) benefits at the expense of another (host), though it typically doesn’t kill the host.
Niche Concepts
Fundamental Niche:
Ideal conditions where an organism thrives without competition, predators, or parasites.
Realised Niche:
The actual conditions and restrictions organisms face due to competition and environmental factors.
Evidence for Past Ecosystems and Evolution
Geological Evidence:
Banded iron formations show the shift from anaerobic to aerobic conditions due to increasing oxygen levels.
Palaeontological Evidence (Fossils):
Fossils, including microfossils, provide clues about past climates and environments.
Ice Core Drilling:
Provides a historical record of gases and dust, revealing past climate conditions.
Dating Methods:
Relative Dating: Determines if a fossil or rock is older or younger than another.
Absolute Dating: Provides a precise age using radiometric methods (e.g., carbon dating).
Extinction Factors
Leading Cause: Habitat loss, overexploitation, introduced species, and disruption of ecological relationships.
Bottleneck Effect: A shrinking population results in reduced genetic variation, making extinction more likely.
Biodiversity
Genetic Diversity: Variation within a species.
Species Diversity: Variety of species in an ecosystem.
Ecosystem Diversity: Variety of ecosystems within a broader area.
Greenhouse Effect and Climate Change
Greenhouse Effect:
Energy absorbed by the Earth is released back into the atmosphere as heat, and greenhouse gases reflect some heat back, keeping the planet warm.
Enhanced Greenhouse Effect:
Human activities, such as burning fossil fuels and deforestation, increase greenhouse gases, disrupting the balance and causing global warming.
