D: Biology = Changes in Living Systems 2.3 Populations Flashcards
What was significant about Rome at the height of its empire?
It was the first metropolis to reach a population of one million people
This growth necessitated the development of resources like aqueducts.
What infrastructure did the Romans build to address their water needs?
Aqueducts
Aqueducts were crucial for bringing water into the city.
Which region did the Romans conquer for its grain production?
Cleopatra’s Egypt
Egypt was known for its ability to produce large quantities of grain.
What problems did Rome face due to its size?
Overcrowding, disease outbreaks, and huge fires
These issues strained resources and led to significant challenges for the city.
What was the population of Rome as the Dark Ages began?
20,000 people
This marked a significant decline from its earlier population of one million.
When did cities again reach the size of Rome?
During the Industrial Revolution of the 1800s
London grew to a population of 1.5 million during this time.
What advances have contributed to longer life expectancy and improved health in modern populations?
Health technology and improved nutrition
These advances include vaccines and pesticides.
What is a consequence of technological advances in health?
Increased human population numbers
This has led to cities of a million or more becoming common.
What challenges may arise as the worldwide human population continues to grow?
Greater problems meeting the demand for resources
This could lead to issues similar to those faced by ancient Rome.
Fill in the blank: The period of history called _______ began after the decline of Rome.
The Dark Ages
This period was characterized by a significant reduction in population and cultural advancement.
True or False: Technological advances have allowed the human population to increase at a slower pace.
False
Technological advances have enabled rapid population growth.
What is the definition of a population in biological terms?
The total number of a certain species found in an area at a particular time.
This concept is crucial for understanding ecological dynamics and species interactions.
Why are bacteria considered good populations to study?
They reproduce rapidly and are simple organisms.
This rapid reproduction allows for quick observation of population dynamics.
How do bacteria reproduce?
By dividing into two new cells after reaching a certain size.
This process is known as binary fission.
What is the doubling time?
The amount of time it takes for a population to double its size.
Doubling time varies by species and environmental conditions.
What is exponential growth?
The rapid growth in population caused by constant doubling.
This type of growth can lead to significant population increases in a short time.
What shape does the graph of exponential growth take?
An exponential curve or J-curve.
This shape indicates unrestricted growth over time.
What happens to a bacterial population in ideal conditions?
It can rapidly increase by constant doubling.
For example, starting with one cell can lead to a large population in a short period.
Fill in the blank: The rapid increase caused by constant doubling in a bacterial population is called _______.
exponential growth.
Understanding this concept is vital for studying population dynamics.
True or False: An exponential curve indicates that a population is growing without restrictions.
True.
This type of growth can occur until environmental limits are reached.
What are the four major factors affecting populations?
The number of births, the number of deaths, immigration, and emigration
What is a closed population?
A group of organisms that exists in a natural or artificial setting where immigration and emigration do not occur, and numbers are only affected by births and deaths
What is an open population?
A group of organisms that exists in a natural setting where births, deaths, immigration, and emigration affect the population numbers
In a closed population, what factors influence the overall size?
Only the number of births and deaths
True or False: In a closed population, immigration and emigration can occur.
False
Fill in the blank: A population affected only by the number of births and deaths is called a _______.
[closed population]
What is the significance of immigration and emigration in open populations?
They can affect the population numbers along with births and deaths
What type of population is represented by a laboratory test tube of bacteria?
Closed population
What type of population exists in a natural setting?
Open population
What is a population explosion?
Sudden exponential growth in a population
This occurs when resources are abundant and there are no predators.
What causes a population crash?
A rapid drop in population size due to resource depletion or starvation
This often follows a population explosion when the carrying capacity is exceeded.
Name three organisms that regularly experience population explosions and crashes.
- Caterpillars
- Rodents
- Insects
These organisms often go through cycles of exponential growth followed by sharp declines.
What happened when rabbits were introduced to Australia in 1859?
The rabbit population grew exponentially, threatening native species
The slow-breeding marsupials could not compete with the fast-eating rabbits.
What is the term for a species that does not normally inhabit an area but is introduced and becomes a threat to biodiversity?
Invasive species
Such species can cause significant ecological damage.
Describe the relationship between vegetation and rabbit population growth on the island.
The rabbit population grew faster than vegetation could replenish
This led to resource depletion and subsequent starvation.
True or False: The introduction of rabbits in Australia had many natural predators.
False
The non-native rabbits faced few natural predators, allowing for unchecked population growth.
Fill in the blank: A rapid increase in the number of individuals in a population is referred to as _______.
Exponential Growth
This term describes the growth pattern before a population crash.
What is the fastest colonization by any mammal recorded in Australia attributed to?
The introduction of non-native rabbits
This phenomenon showcased the impact of invasive species on ecosystems.
What limits the size of a population before it surpasses its carrying capacity?
Factors such as disease, predators, natural disasters, and competition for resources.
What shape does the graph of a population limited by factors take?
An S-curve.
True or False: The exponential growth of a population can continue indefinitely.
False.
Fill in the blank: The maximum number of individuals that an environment can sustain is called _______.
[carrying capacity].
What does an S-curve graph indicate in terms of population growth?
It indicates that the population stabilizes at a size that defines the carrying capacity.
What happens to populations that reach their carrying capacity?
They stabilize rather than experience a crash.
What is the difference between S-curve and J-curve in population growth?
S-curve shows stabilization at carrying capacity, while J-curve shows exponential growth without limits.
What is the term for the factors that help limit population size?
Limiting factors.
Who identified and described many factors affecting natural populations?
Thomas Malthus
Malthus is known for his contributions to population theory.
In what year did Thomas Malthus publish his essay titled ‘Essay on the Principle of Population’?
1789
This work is considered influential and controversial.
What is the main thesis of Malthus’s ‘Essay on the Principle of Population’?
There are natural checks and balances in nature that regulate population numbers
These checks include famine and diseases.
Fill in the blank: Malthus argued that unchecked population growth will exceed the amount of _______ available.
food
This can lead to a population crash.
True or False: Malthus believed that famine and diseases are factors that help maintain constant population numbers.
True
These elements are considered natural checks in his theory.
What happens to populations when growth exceeds available resources according to Malthus?
A crash in numbers will occur
This is a consequence of exceeding food availability.
What are some examples of natural checks and balances identified by Malthus?
- Famine
- Diseases
These factors can limit population growth.
Fill in the blank: Malthus’s theory suggests that population growth is _______ without checks.
exponential
This growth pattern can lead to unsustainable population sizes.
What was Malthus’s concern regarding population?
Malthus expressed concern that while the human population grows, resources do not grow at the same rate.
Fill in the blank: Malthus believed that the human population grows _______.
[exponentially]
True or False: Malthus believed that resources would increase at the same rate as the population.
False
What concept is associated with Malthus’s theory on population?
The concept of population growth versus resource availability.
List two key elements of Malthus’s population theory.
- Population growth
- Resource limitation
Fill in the blank: According to Malthus, population increases _______ while resources increase _______.
[exponentially], [arithmetically]
What is the implication of Malthus’s theory on societal growth?
If population growth exceeds resource growth, it may lead to famine and societal collapse.
What term describes the maximum population that an environment can sustain?
[carrying capacity]
True or False: Malthus’s theory supports the idea that technological advancements can indefinitely increase resources.
False
What demographic transition stage is characterized by high birth and death rates?
[Stage 1]
What are the four major factors that affect populations?
- Births
- Deaths
- Immigration
- Emigration
These factors contribute to the dynamics of population changes.
What is a closed population?
A population affected only by the number of births and deaths
Closed populations do not experience immigration or emigration.
What distinguishes an open population from a closed population?
An open population experiences immigration and emigration in addition to births and deaths
This allows for changes in population size due to movement of individuals.
What type of growth do organisms often experience when introduced into a new area?
Exponential growth
This growth can lead to significant increases in population size under favorable conditions.
What does exponential population growth graphically represent?
A J-curve
This curve indicates rapid growth until resources become limited.
What can result from exponential population growth when resources are depleted?
A crash in population size
This occurs when the environment can no longer support the population.
What does the S-curve represent in population dynamics?
A leveling off at the carrying capacity
The carrying capacity is the maximum population size that an environment can sustain.
Why is the exponential growth of the human population a concern?
It raises concerns about the supply of resources
Rapid population growth can lead to resource depletion and sustainability issues.
What environment do most snails prefer?
Moist environments such as freshwater ponds, lakes, streams, and creeks
Where is the Banff Springs snail exclusively found?
In the five thermal springs on Sulphur Mountain
What is the conservation status of the Banff Springs snail?
It is the most endangered species in Banff National Park
What do Banff Springs snails depend on for survival?
A steady supply of thermal spring water with high mineral content and sufficient hydrogen sulfide
How do snails move?
By creeping on a single ‘foot’ located under their body
What is unique about a snail’s foot?
It is a band of muscles that expands and contracts in a rippling movement
Where are a snail’s eyes located?
On the top of its tentacles
What additional sensory feature do many land snails possess?
An additional pair of tentacles equipped with sense organs
How do snails consume food?
Food is mashed between a hard ridge on the roof of the mouth and the tongue
What is remarkable about a snail’s tongue?
It contains from hundreds to thousands of tiny teeth
Fill in the blank: Snails carry their _______ on their backs.
shelter
True or False: Snails move quickly, as implied by the term ‘a snail’s pace.’
False
What are the characteristics of land snail shells?
Intricate patterns, combination of colours, textures, and overall shape
These features give each shell its own character and artistic appeal.
What functions do snail shells serve?
Protection against predators and retaining moisture
Snail shells are not only aesthetically pleasing but also crucial for survival.
How long have snails existed on Earth?
Nearly 500 million years
Snails have adapted to a wide variety of environments over this extensive time period.
What type of climate do different species of land snails thrive in?
Warm and moist climate
This environment supports diverse species with unique shell patterns.
True or False: Snail shells are purely decorative.
False
They serve important functions such as protection and moisture retention.
Fill in the blank: The characteristics of snails have allowed them to survive in a wide variety of _______.
[environments]
This adaptability has contributed to their long-term presence on Earth.
What has Earth experienced over geological time?
Dramatic changes
These changes have influenced the evolution of abundant life forms, including snails.
What era is characterized by the presence of trilobites?
Paleozoic
The Paleozoic era is known for the diversity of life forms, particularly trilobites.
What is the age of the Precambrian era?
590 million years ago
The Precambrian era covers a vast period before the Paleozoic era.
Which life forms are commonly found in the fossil record due to their well-preserved shells?
Snails
Snail fossils are abundant because their shells are durable and often well-preserved.
How do the slow-moving characteristics of land snails benefit fossil studies?
They tend to be restricted to a particular habitat
This allows for the accumulation of many generations’ remains in one location.
What significant change in snail fossils was observed over a period of 15,000 years?
Morphological changes
The morphology refers to the detailed shape and form of the snail shells.
What geological period follows the Mesozoic era?
Cenozoic
The Cenozoic era is the most recent geological time period.
Which group of animals was prominent during the Mesozoic era?
Dinosaurs
Dinosaurs were the dominant terrestrial vertebrates during the Mesozoic era.
Fill in the blank: The fossil record is the record of all _______ on Earth as preserved by fossils.
life forms
This includes all known fossils, whether excavated or still buried.
What is the significance of the fossil record?
It provides a historical account of life on Earth
The fossil record helps scientists understand the evolution and extinction of species.
What is the meaning of ‘morphology’ in the context of fossils?
The detailed shape and form of an animal
Morphology can reveal evolutionary changes over time.
True or False: Ammonites were abundant during the Cenozoic era.
False
Ammonites were primarily abundant during the Mesozoic era.
Which life forms are noted to exist in the Cenozoic era?
Mammals
The Cenozoic era is often referred to as the age of mammals.
What is gradualism?
The theory that changes to organisms in a population occur gradually over time.
Gradualism explains that big changes result from the accumulation of many slight alterations over a long period.
What is punctuated equilibrium?
The theory that changes to organisms in a population occur suddenly after a period of little or no change.
Punctuated equilibrium demonstrates the sudden appearance of new forms with different shapes.
What visual representation is used to show slight changes between layers in gradualism?
Diagonal lines.
Diagonal lines indicate slight shifts in shape between layers.
What visual representation is used to show major changes between adjacent layers in punctuated equilibrium?
Horizontal lines.
Horizontal lines indicate more rapid changes that do not occur gradually.
Fill in the blank: Gradualism explains that big changes within a population are the result of an accumulation of many slight alterations that occur over a _______.
long time.
True or False: Gradualism and punctuated equilibrium both explain the same rate of change in populations.
False.
The key difference is the rate of change: gradualism is gradual, while punctuated equilibrium involves sudden changes.
What happens to snail shells in the model of gradualism?
They change slightly over time, with shells in higher layers shifted only slightly to the left or right.
This gradual change is depicted with diagonal lines.
What occurs in the model of punctuated equilibrium?
Shells may remain relatively unchanged and then suddenly diverge into forms with different shapes.
This sudden divergence is depicted with horizontal lines.
Describe the key difference between gradualism and punctuated equilibrium.
The rate of change: gradualism involves slow changes, while punctuated equilibrium involves rapid changes.
Gradualism accumulates slight alterations; punctuated equilibrium shows sudden new forms.
What is the primary focus of the study on bighorn sheep in Alberta’s Rocky Mountains?
The impact of hunting on male bighorn sheep morphology
Hunters are allowed to shoot rams with fully-curved horns, leading to a reduction in size and horn length in subsequent generations.
What characteristic makes a bighorn sheep a trophy sheep?
Horns that have curved to make almost a complete circle
Trophy sheep are often the largest and strongest males.
What effect does hunting have on the bighorn sheep population?
Encourages smaller and weaker males to breed
Larger males are systematically removed from the population before they can reproduce.
What has data collected over the past 30 years shown regarding male bighorn sheep?
Changes in morphology, including reduced body mass and shorter horns
These changes are linked to hunting practices.
What is punctuated equilibrium?
A rapid rate of change in species characteristics compared to geological time
The changes observed in bighorn sheep morphology serve as an example.
What drives changes in the physical characteristics of snails?
Changes in genetic information
Both gradualism and punctuated equilibrium can be seen in these changes.
What types of traits can vary within a population due to genetic changes?
- Physical
- Behavioral
- Biochemical
Subtle changes in genetic information account for these variations.
What results from larger changes in genetic information?
The development of new species
This indicates a significant alteration in the genetic makeup of organisms.
True or False: It is legal to hunt bighorn sheep with less curl than indicated by the green dotted line.
False
The hunting regulations specify the minimum horn curl for legal hunting.
What has the development of the scientific discipline of genetics resulted in?
A better understanding of how and why the variation of a trait occurs within a population
How many sets of genes does each organism have in each cell?
Two sets of genes
What do genes determine?
Most of an organism’s characteristics
Where does one set of genes present in each cell come from?
Each of the offspring’s parents
What are genes?
Instructions encoded in the larger sections of the DNA molecule that result in an organism’s traits
What is the basic unit of inheritance?
Gene
What results in the many varieties of a trait seen in a population?
Mixing traits
What do genes tell an organism’s body?
How to look, when to grow, and what things to make
What biological process involves the recopying of genetic instructions?
Cell reproduction or creation of sex cells
What can mistakes during the recopying of genetic instructions result in?
Mutations
What is a mutation?
A change in a genetic instruction
What are some causes of mutations?
Exposure to radioactive substances and cigarette smoke
True or False: Most mutations are harmful and affect the characteristics of an organism.
False
What increase the occurrence of mutations according to studies?
Exposure to ultraviolet (UV) rays
Fill in the blank: Genes are a set of ________ coded in a chemical form.
Instructions
What is a change in instructions from a gene called?
Mutation
What is the typical population stability of land snails in a stable ecosystem?
Stable due to limited resources
Resources needed to support population are limited, leading to a struggle for survival.
What is a significant factor contributing to the survival of land snails?
Predation
Predation is especially intense during the nesting season for birds.
Why are snails considered an excellent food source for birds?
They provide calcium
Calcium is essential for birds preparing to lay eggs.
What distinguishes banded snails from unbanded snails?
Banded snails have lighter-colored bands
Unbanded snails lack these bands.
How does coloration and banding on snail shells affect their survival?
It helps them blend into surroundings
This ability to blend in aids in avoiding predators.
What do researchers study to understand the traits of land snails?
Current populations and shell patterns
They determine how color and patterns are inherited.
What do offspring of land snails inherit from their parents?
Color and patterns of banding
These traits impact their ability to avoid being preyed upon.
Fill in the blank: Only a tiny fraction of snails ______ from each generation.
survives
What is adaptation?
Any structural trait or behavioural trait that improves an organism’s success at surviving and reproducing in a particular environment
Adaptations can be physical characteristics or behaviors that enhance survival and reproduction.
What does a change in the snail population, such as having more or fewer light-coloured bands, signify?
It is called an adaptation
Adaptations allow species to respond to environmental changes.
What does each different type of snail shell in The Desktop Fossil Record represent?
A new snail species
The variation in appearance signifies evolutionary changes over time.
Why might the appearance of snail shells have changed over time?
Due to adaptations to environmental changes
Various factors such as climate, food sources, and predators can drive these changes.
What will be explored in the next lesson regarding Charles Darwin?
His theory explaining how adaptations over time can lead to new species
Darwin’s theory of evolution by natural selection is foundational to understanding species change.
Fill in the blank: Adaptations can lead to _______ in some layers and then no longer appear in others.
new species
This reflects the process of extinction and the emergence of new species over geological time.
What are genes?
Basic units of inheritance passed from parents to offspring determining characteristics
Genes influence physical traits and other characteristics of an organism.
What do mutations refer to?
Changes that occur to a gene which can be harmful, beneficial, or neutral
Mutations are a source of genetic variation within a population.
What are variations in a population?
Differences among individuals with respect to a trait
Variations are often the result of mutations.
Define adaptations.
Inherited characteristics that allow an organism to survive better in a specific environment
Adaptations can be physical or behavioral.
What types of adaptations exist?
Physical or behavioral adaptations
These adaptations help organisms reproduce, find food, or avoid predation.
True or False: Successful organisms are poorly adapted to their habitat.
False
Successful organisms are well adapted to their environment.
