Lesson 3.1

Populations
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Slide 1: Slide
BiologieMiddelbare schoolvwoLeerjaar 4

This lesson contains 20 slides, with interactive quizzes, text slides and 2 videos.

time-iconLesson duration is: 30 min

Items in this lesson

Populations

Slide 1 - Slide

What is a population?

Slide 2 - Open question

With reference to the following statements about a woodland ecosystem. Which statement describes a population?
A
All the oak trees
B
All the plants
C
All the plants and animals

Slide 3 - Quiz

Population size
immigration
emigration
death
birth

Slide 4 - Drag question

Population growth
Involves:
  1. Biotic potential: max reproduction rate given all the resources the population needs
  2. Environmental resistance: all factors that may limit growth. (scarcity of resources, predation, climate conditions etc)
  3. Carrying capacity: max population size that can be supported by a particular environment

Slide 5 - Slide

Population curves
  • J-curve: often seen in fast reproducing organisms that colonise a new environment. Exponential growth followed by hitting a limiting factor and often the population crashes
  • S-curve: Exponential growth until population hits environmental resistance and stabilises around the carrying capacity

Slide 6 - Slide

Carrying capacity
Environmental resistance
Few reproducing individuals
Exponential growth

Slide 7 - Drag question

What is population density?

Slide 8 - Open question

Environmental resistance
Can be:
  • Density indepent: these factors influence all organism in a population irrespective of population density. Can be biotic of abiotic
  • Density dependent: the influence of these factors on population size depend on the density of the population. Usually the higher the density the bigger the impact of these factors. Always biotic

Slide 9 - Slide

Density independent
Density dependent
Light
parasitism
earthquake
competition
disease

Slide 10 - Drag question

Measuring population
Size and density

Slide 11 - Slide

Why?
  • Knowing if population is increasing or decreasing
    - Useful for predicting future developments 
    - Understanding if conservation is working

Slide 12 - Slide

How?
  • Ideally exact numbers, but total count is often not possible
  • Therefor, estimates of size
  • Method used for estimates mainly depends on the type of organism
  • Plants/ not very mobile animals: quadrat or transect (first video)
  • Mobile animals: mark-recapture (second video)

Slide 13 - Slide

Slide 14 - Video

What is a square called that we use to sample populations?
A
grid
B
quadrat
C
cube
D
quarter

Slide 15 - Quiz

These four 1m2 squared quadrats were place in a 8m2 garden. Estimate the total population of flowers in the whole garden.
A
16
B
8
C
40
D
20

Slide 16 - Quiz

Slide 17 - Video

Which one of these is a correct assumption you need to make about a population between samplings?
A
It is a closed population
B
It won't rain between samplings
C
There are lots of deaths
D
There are lots of births

Slide 18 - Quiz

If 50 crabs were captured and marked and then released and then a few days later 25 were caught and of those 5 were marked. What would the estimate of the population be?
A
500
B
250
C
75
D
200

Slide 19 - Quiz

Homework
  • Read pages 440-441, 450-451
  • Complete this lessonup
  • Complete worksheet population size on Classroom

Slide 20 - Slide