Animal and Plant Cells: Features, Processes, and Energy Transfer
Animal and Plant Cells: Key Features
Animal Cells:
- Nucleus: Controls the activities of the cell.
- Cytoplasm: Where chemical reactions take place.
- Cell Membrane: Controls the passage of substances.
- Mitochondria: Structures in the cytoplasm responsible for energy production.
- Ribosomes: Where protein synthesis takes place.
Plant Cells:
- All have a cell wall made of cellulose, which strengthens the cell and provides support.
Additional Features in Plant Cells
- Chloroplasts: Found in all green parts of plants, responsible for photosynthesis.
- Vacuole: A space in the cytoplasm filled with cell sap.
Specialized Cells and Their Functions
- Enzymes: Proteins that control the rate of specific reactions.
- Hair Cells: Enable plants to take in the water they need.
- Cone Cells: Make it possible to see in color.
- Fat Cells: Important for helping animals survive when food is scarce.
- Sperm Cells: Contain the genetic information to pass on to offspring.
Key Biological Processes
Diffusion
The net movement of particles from an area of high concentration to an area of lower concentration.
Osmosis
The movement of water across a semipermeable membrane from an area of high concentration to an area of low concentration.
Photosynthesis
CO2 + H2O + Sunrays → Glucose + O2
Limiting Factors in Photosynthesis
Light intensity, temperature, and CO2 levels.
How Plants Use Glucose
Plants make glucose during photosynthesis and use it for respiration, providing energy for cell functions, growth, and reproduction.
Respiration
Glucose + O2 → CO2 + H2O
Uses of Glucose
For respiration, making different biomolecules, and storage as starch.
Minerals for Plants
Plants need nitrogen for making proteins and magnesium to make chlorophyll.
Ecology and Energy Transfer
Biomass
The mass of living materials in an animal or plant.
Food Chain
The method in which energy in the biomass made by plants is passed to the animals that eat the plants.
Pyramids
- Pyramid of Numbers: Counting the number of organisms at each level to compare them.
- Pyramid of Biomass: Shows what is happening in food chains more accurately.
Sankey Diagrams
Show how energy is transferred in a system.
Energy Use in Different Organisms
- Herbivores: Heat (2), movement (4), feces (8). They process a lot of food.
- Carnivores: Heat (2.5), movement (5), feces (3). They must move a lot to hunt.
- Cold-Blooded Animals: Heat (1), movement (5), feces (3). Energy loss in feces due to heat production.
- Warm-Blooded Animals: Heat (8), movement (6), feces (3). High heat production influenced by climate.
Food Production
Growing plants and eating them directly is most efficient. Introducing extra stages in a food chain means less energy reaches the end consumer. There would be more food if we only ate plants, as we would lose less energy and need to eat less. Ways to reduce energy loss in growing animals include limiting movement and controlling temperature.
Decomposition and Recycling
Decay
A process in which remains and wastes of living things are decomposed and recycled.
Detritus Feeders
Organisms that eat remains and wastes (e.g., worms and maggots).
Decomposers
Bacteria and fungi that break down wastes.
Scavengers
Organisms that consume dead animals (e.g., vultures).
Factors Affecting Decomposition
Temperature
High temperatures can denature enzymes, slowing down decomposition.
Moisture
Moisture makes it easier for organisms to dissolve their food and prevents them from drying out.
Oxygen
The presence of oxygen makes the decomposition process faster.