BIOLOGY NOTES IEB
MATRIC
Summaries of Mind Action Series Life Sciences Textbook Grade 12
pg. 0
,Table of Contents
Chapter 1...............................................................................................................................................1
Environmental Studies...........................................................................................................................2
Chapter 2 Life Processes in animals and plants.....................................................................................4
Endocrine System..................................................................................................................................5
Reproduction in Flowering Plants..........................................................................................................8
Reproductive Animal Strategies...........................................................................................................11
Human Reproduction...........................................................................................................................12
Chapter 3 Life at Molecular, Cellular and Tissues Level.......................................................................18
DNA – Code of life................................................................................................................................18
Chromosomes and Meiosis..................................................................................................................20
Genetics and Genetic Engineering.......................................................................................................22
Gene Therapy......................................................................................................................................24
GM Crops.............................................................................................................................................25
Chapter 4 Evolution.............................................................................................................................26
Origin of an Idea About Origins...........................................................................................................26
Fundamental Aspects of Evolution......................................................................................................28
Formation of New Species...................................................................................................................29
Hominid Studies...................................................................................................................................31
Evolution in Present Times..................................................................................................................37
Chapter 1
pg. 1
,Environmental Studies
Levels of population ecology
Individual – one organism.
Population – many individuals of the same species in a specific area. (Populations fluctuate
seasonally depending on the amount of recourses available.)
Community – many populations interacting within an area.
Ecosystem – biotic and abiotic factors interacting within an area.
What affects the size of a population?
Natality – birth rate.
Mortality – death rate.
Immigration – individuals move into a population and stay.
Emigration – individuals leave a population and do not return.
A closed population has no immigration or emigration, the only parameters affecting any change in
population numbers will be births or deaths. E.g.(fish in a small pond)
Environmental Resistance
The total number of factors that stop a population from reproducing at its maximum rate.
Limiting factors on population growth:
These regulate the growth of a population. These limiting factors build up environmental resistance.
Density independent factors – physical factors (rain), catastrophic factors (tsunami).
Density dependent factors – have a greater effect when the population density is high. For
example – recourse and food.
Populations
Stable populations – fluctuate around the carrying capacity.
Unstable populations – population exceeds the carry capacity. (Habitat deteriorates rapidly)
Population Estimation
Random sampling is important as it allows for a fair distribution of organisms in an environment.
Improves accuracy.
Direct: Counting each organism – Census – Large area = inaccurate, takes a long time.
Indirect:
Quadrat method = (Average Number of Organisms Per Quad x Total Area) / size of a single
quad. Best suited for stationary or slow-moving organisms.
Mark Recapture method = (Number of First Catch x Number of Second Catch) / Number in
Second Catch Already Marked. Best suited for a Closed population.
Predator-prey Relationships
Changes in the population size of one species can drastically affect another.
There should always be more prey than predators as the prey support the predators.
Predators help by: regulating amount of prey, keep prey genetically fit, increase the
biodiversity in the environment.
Lion and Zebra Relationship
Both the Lion (predator) and the Zebra (prey) evolve adaptations to outwit the other.
pg. 2
, One of these adaptations is speed of movement.
The fast lions eat the prey, while the fast prey escape the lions and survive.
This is an example of co-evolution, both species help each other genetically strong.
Shark and Fish Relationship
Sharks are at the top of the food chain; the sharks keep the fish healthy and in balance in the
ecosystem.
The sharks strengthen the gene pool of the fish and prevent the spread of disease in the fish.
The fish produce strong, healthy offspring. This results in a large amount of healthier, more
genetically fit fish.
How food webs impact on populations
Food webs control the ecosystem.
If the predators are removed from the food webs, their prey population would rapidly
increase creating problems.
Competition – when two or more individuals compete for the same resources that are shortly
supplied. It is a powerful force effecting the growth, distribution, and size of population in nature.
Different Types of Competitions
Intraspecific competition – individuals in the same species compete for resources. Most
intense form as the individuals have similar habitats.
Interspecific competition – occurs between individuals of different species.
Ecological Niches
Represents all required elements species need to survive and reproduce.
Examples – tolerate environment (temperature), obtain nutrients and energy, cope with
competition, avoid predators.
Competitive - Both types are consequences of interspecific competition.
1. Competitive exclusion – 1 species survives, and the other species disappears.
2. Competitive co-existence – they use the resources differently. (Resource partitioning)
Ways of reducing competition in animals
1. Different times – mice eat insects during the day, frogs eat insects during the night.
2. Different parts of the prey – different fish feed at different depths in a lake.
Ways of reducing competition in plants
Pioneer species and young trees are found growing in the gaps between trees.
Example
Giraffes eat the high branches on trees and kudu eat the lower branches on the same trees.
Ecological succession – a predictable pattern of gradual change over time in the types of species in a
community following a disturbance.
1. Primary – Beginning (nothing existed before hand) No previous plants in this area.
pg. 3
MATRIC
Summaries of Mind Action Series Life Sciences Textbook Grade 12
pg. 0
,Table of Contents
Chapter 1...............................................................................................................................................1
Environmental Studies...........................................................................................................................2
Chapter 2 Life Processes in animals and plants.....................................................................................4
Endocrine System..................................................................................................................................5
Reproduction in Flowering Plants..........................................................................................................8
Reproductive Animal Strategies...........................................................................................................11
Human Reproduction...........................................................................................................................12
Chapter 3 Life at Molecular, Cellular and Tissues Level.......................................................................18
DNA – Code of life................................................................................................................................18
Chromosomes and Meiosis..................................................................................................................20
Genetics and Genetic Engineering.......................................................................................................22
Gene Therapy......................................................................................................................................24
GM Crops.............................................................................................................................................25
Chapter 4 Evolution.............................................................................................................................26
Origin of an Idea About Origins...........................................................................................................26
Fundamental Aspects of Evolution......................................................................................................28
Formation of New Species...................................................................................................................29
Hominid Studies...................................................................................................................................31
Evolution in Present Times..................................................................................................................37
Chapter 1
pg. 1
,Environmental Studies
Levels of population ecology
Individual – one organism.
Population – many individuals of the same species in a specific area. (Populations fluctuate
seasonally depending on the amount of recourses available.)
Community – many populations interacting within an area.
Ecosystem – biotic and abiotic factors interacting within an area.
What affects the size of a population?
Natality – birth rate.
Mortality – death rate.
Immigration – individuals move into a population and stay.
Emigration – individuals leave a population and do not return.
A closed population has no immigration or emigration, the only parameters affecting any change in
population numbers will be births or deaths. E.g.(fish in a small pond)
Environmental Resistance
The total number of factors that stop a population from reproducing at its maximum rate.
Limiting factors on population growth:
These regulate the growth of a population. These limiting factors build up environmental resistance.
Density independent factors – physical factors (rain), catastrophic factors (tsunami).
Density dependent factors – have a greater effect when the population density is high. For
example – recourse and food.
Populations
Stable populations – fluctuate around the carrying capacity.
Unstable populations – population exceeds the carry capacity. (Habitat deteriorates rapidly)
Population Estimation
Random sampling is important as it allows for a fair distribution of organisms in an environment.
Improves accuracy.
Direct: Counting each organism – Census – Large area = inaccurate, takes a long time.
Indirect:
Quadrat method = (Average Number of Organisms Per Quad x Total Area) / size of a single
quad. Best suited for stationary or slow-moving organisms.
Mark Recapture method = (Number of First Catch x Number of Second Catch) / Number in
Second Catch Already Marked. Best suited for a Closed population.
Predator-prey Relationships
Changes in the population size of one species can drastically affect another.
There should always be more prey than predators as the prey support the predators.
Predators help by: regulating amount of prey, keep prey genetically fit, increase the
biodiversity in the environment.
Lion and Zebra Relationship
Both the Lion (predator) and the Zebra (prey) evolve adaptations to outwit the other.
pg. 2
, One of these adaptations is speed of movement.
The fast lions eat the prey, while the fast prey escape the lions and survive.
This is an example of co-evolution, both species help each other genetically strong.
Shark and Fish Relationship
Sharks are at the top of the food chain; the sharks keep the fish healthy and in balance in the
ecosystem.
The sharks strengthen the gene pool of the fish and prevent the spread of disease in the fish.
The fish produce strong, healthy offspring. This results in a large amount of healthier, more
genetically fit fish.
How food webs impact on populations
Food webs control the ecosystem.
If the predators are removed from the food webs, their prey population would rapidly
increase creating problems.
Competition – when two or more individuals compete for the same resources that are shortly
supplied. It is a powerful force effecting the growth, distribution, and size of population in nature.
Different Types of Competitions
Intraspecific competition – individuals in the same species compete for resources. Most
intense form as the individuals have similar habitats.
Interspecific competition – occurs between individuals of different species.
Ecological Niches
Represents all required elements species need to survive and reproduce.
Examples – tolerate environment (temperature), obtain nutrients and energy, cope with
competition, avoid predators.
Competitive - Both types are consequences of interspecific competition.
1. Competitive exclusion – 1 species survives, and the other species disappears.
2. Competitive co-existence – they use the resources differently. (Resource partitioning)
Ways of reducing competition in animals
1. Different times – mice eat insects during the day, frogs eat insects during the night.
2. Different parts of the prey – different fish feed at different depths in a lake.
Ways of reducing competition in plants
Pioneer species and young trees are found growing in the gaps between trees.
Example
Giraffes eat the high branches on trees and kudu eat the lower branches on the same trees.
Ecological succession – a predictable pattern of gradual change over time in the types of species in a
community following a disturbance.
1. Primary – Beginning (nothing existed before hand) No previous plants in this area.
pg. 3
