BiologyChapter 15: Ecology
Population and Community
Population size: count, sample (quadrat named), mark-release-recapture named as a formula idea — N = (M x C) / R school, for moving animals,
Learning objectives
- Explain population and community in clear biological language.
- Distinguish 1. counting from 2. curves.
- Use the key terms to answer a short Federal Board exam question.
Definition
Population size: count, sample (quadrat named), mark-release-recapture named as a formula idea — N = M x CR school, for moving animals, with assumptions (no death, random mix). Growth: lag, exponential, then carrying capacity K (S-curve). Factors: density-dependent (disease, food) vs independent (storm). Community: succession next page. Predator-prey oscillation named (Lynx-hare cartoon). Population ecology uses counting methods and growth models. Community ecology studies species interactions: competition, predation, mutualism, and succession over time.
Mathematical form
N = 40 x 5010 = 200.
N = M x CR school
M = 40). Catch 50
C = 50
Important terms
- POPULATION AND COMMUNITY
- Population size: count, sample (quadrat named), mark-release-recapture named as a formula idea — N = (M x C) / R school, for moving animals, with assumptions (no death, random mix).
- 1. COUNTING
- Quadrat for plants: random, several, mean x area.
- 2. CURVES
- J-curve then crash, or S to K.
Relationship
- K = carrying capacity
Overview
How many, then what limits:
Counting
Quadrat for plants: random, several, mean x area. Mark-recapture assumptions fail if marks harm or animals learn traps. These are exam methods in words, not a field-poaching guide.
Examples Random quadrats · N = MC/R school · Open vs closed population
Curves
J-curve then crash, or S to K. r-selected vs K-selected named if the book (many young vs few cared). Human population is a graph in many books; treat people with dignity.
Examples Food, space, waste · Density-dependent disease · Storm is independent
WHAT — POPULATION AND COMMUNITY
Population size: count, sample (quadrat named), mark-release-recapture named as a formula idea — N = M x CR school, for moving animals, with assumptions (no death, random mix). Growth: lag, exponential, then carrying capacity K (S-curve). Factors: density-dependent (disease, food) vs independent (storm). Community: succession next page. Predator-prey oscillation named (Lynx-hare cartoon). Population ecology uses counting methods and growth models. Community ecology studies species interactions: competition, predation, mutualism, and succession over time.
WHY — Why this topic matters
POPULATION AND COMMUNITY is an independent FBISE learning unit because students must connect its structures and processes with their biological functions and examples.
HOW — How it works
COUNTING: Quadrat for plants: random, several, mean x area. Mark-recapture assumptions fail if marks harm or animals learn traps. These are exam methods in words, not a field-poaching guide. Examples: Random quadrats; N = MC/R school; Open vs closed population. CURVES: J-curve then crash, or S to K. r-selected vs K-selected named if the book (many young vs few cared). Human population is a graph in many books; treat people with dignity. Examples: Food, space, waste; Density-dependent disease; Storm is independent. Worked mark-recapture (school). Mark 40 (M = 40). Catch 50, 10 marked (C = 50, R = 10). N = 40 x 5010 = 200.
Worked example
- Worked mark-recapture (school).
- Mark 40 (M = 40).
- Catch 50, 10 marked (C = 50, R = 10).
- N = 40 x 5010 = 200.
In simple words
Sampling ideas for exams. Not a how-to to trap wildlife illegally.
Key points
- K = carrying capacity
- quadrat / mark-recapture names
- sample then multiply
- resources cap K
Exam preparation
Exam Focus
Quick revision
Revision Zone
Review the key facts, formulas and checks before you move on.Population and Community
Sticky Notes · Quick Revision
Core Idea
- Population size: count, sample (quadrat named), mark-release-recapture named as a formula idea — N = M x CR school, for moving animals, with assumptions (no death, random mix). Growth: lag, exponential, then carrying capacity K (S-curve). Factors: density-dependent (disease, food) vs independent (storm). Community: succession next page. Predator-prey oscillation named (Lynx-hare cartoon). Population ecology uses counting methods and growth models. Community ecology studies species interactions: competition, predation, mutualism, and succession over time.
1. COUNTING
- Quadrat for plants: random, several, mean x area. Mark-recapture assumptions fail if marks harm or animals learn traps. These are exam methods in words, not a field-poaching guide.
2. CURVES
- J-curve then crash, or S to K. r-selected vs K-selected named if the book (many young vs few cared). Human population is a graph in many books; treat people with dignity.
Exam Example
- Worked mark-recapture (school).
- Mark 40 (M = 40).
- Catch 50, 10 marked (C = 50, R = 10).
- N = 40 x 5010 = 200.
Common Misconception
- Do not treat 1. COUNTING and 2. CURVES as the same idea; each explains a different part of the topic.
FBISE Exam Check
- Define population and community, explain the two key parts, and use the correct biological terms.
- Exam reminder: Worked mark-recapture (school).
60-second revision
- Population size: count, sample (quadrat named), mark-release-recapture named as a formula idea — N = M x CR school, for moving animals, with assumptions (no death, random mix).
- 1. COUNTING: Quadrat for plants: random, several, mean x area.
- 2. CURVES: J-curve then crash, or S to K.
- Exam reminder: Worked mark-recapture (school).
Did you understand this topic?
Your answer is saved with your learning record. It does not mark the topic as mastered.