Biology Chapter on Variation and Selection
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Questions and Answers

Which type of variation gives rise to a smooth bell-shaped curve when plotted as a graph?

  • Genetic variation
  • Environmental variation
  • Continuous variation (correct)
  • Discontinuous variation

Blood group is an example of continuous variation.

False (B)

Name one example of genetic variation in humans.

Blood group or eye colour

Phenotypic variation can be genetic, caused entirely by ______ or environmental, caused entirely by the environment.

<p>genes</p> Signup and view all the answers

Match the following types of variation with their characteristics:

<p>Continuous variation = Gives rise to a smooth bell-shaped curve Discontinuous variation = Gives rise to a step-shaped graph Genetic variation = Controlled entirely by genes Environmental variation = Caused by the environment in which the organism lives</p> Signup and view all the answers

What is the primary reason white shelled snails survive longer than their black or grey counterparts?

<p>They are better camouflaged (C)</p> Signup and view all the answers

The term 'survival of the fittest' refers to the ability of organisms to reproduce more successfully than others in their population.

<p>True (A)</p> Signup and view all the answers

What happens to the allele for white shells over generations in the snail population?

<p>It gets passed onto offspring more frequently.</p> Signup and view all the answers

In natural selection, variations in a population can arise from __________.

<p>chance mutations</p> Signup and view all the answers

Match the following concepts with their descriptions:

<p>Natural selection = The process through which organisms better adapted to their environment tend to survive and produce more offspring. Survival of the fittest = A term that explains why certain organisms thrive in competition. Camouflage = The ability of an organism to blend in with its environment. Allele = A variant form of a gene that governs a specific trait.</p> Signup and view all the answers

What distinguishes continuous variation from discontinuous variation?

<p>Discontinuous variation has distinct categories, while continuous can be measured on a scale. (D)</p> Signup and view all the answers

Phenotypic variation can include traits that are influenced by both genetic and environmental factors.

<p>True (A)</p> Signup and view all the answers

Give two examples of characteristics that exhibit continuous variation.

<p>height, mass</p> Signup and view all the answers

In discontinuous variation, groups are categorized distinctly such as blood types A, B, AB, or ___ .

<p>O</p> Signup and view all the answers

Match the types of variation with their examples:

<p>Continuous Variation = Finger Length Discontinuous Variation = Gender</p> Signup and view all the answers

What graph shape is typically produced by plotting continuous variation?

<p>A smooth bell curve (D)</p> Signup and view all the answers

Discontinuous variation can have many ‘in-between’ values.

<p>False (B)</p> Signup and view all the answers

Define genetic variation in your own words.

<p>Genetic variation refers to differences in genes among individuals of the same species.</p> Signup and view all the answers

What is one adaptation of xerophytes to minimize water loss?

<p>Needle-shaped small leaves (B)</p> Signup and view all the answers

Only large plants can survive in deserts.

<p>False (B)</p> Signup and view all the answers

Who put forward the theory of natural selection?

<p>Charles Darwin</p> Signup and view all the answers

The process where individuals with favorable traits are more likely to survive and reproduce is known as __________.

<p>natural selection</p> Signup and view all the answers

Match the adaptations of xerophytes with their purposes:

<p>Small leaves = Reduce water loss Shallow roots = Quickly absorb water Thickened stems = Store water Needle shape = Minimize evaporation surface</p> Signup and view all the answers

What environmental condition do xerophytes primarily adapt to?

<p>Deserts (C)</p> Signup and view all the answers

Natural selection can lead to changes in the alleles of a population over time.

<p>True (A)</p> Signup and view all the answers

What leads to competition among individuals in an environment?

<p>Limited resources</p> Signup and view all the answers

What is the primary consequence of natural selection?

<p>It helps organisms become better suited to their environment. (B)</p> Signup and view all the answers

Natural selection leads to a change in the characteristics of a population over time.

<p>True (A)</p> Signup and view all the answers

What is defined as the change in adaptive features of a population over time due to natural selection?

<p>Evolution</p> Signup and view all the answers

The development of __________ resistance by bacteria is an example of adaptation by natural selection.

<p>antibiotic</p> Signup and view all the answers

Match the following components with their roles in natural selection:

<p>Variation = Differences in traits among individuals in a population Mutation = Changes in DNA that can provide new traits Selection = Process that favors individuals with advantageous traits Adaptation = The adjustment of organisms to their environment</p> Signup and view all the answers

If the environment changes, what might occur in terms of natural selection?

<p>Selection will favor individuals with different characteristics. (B)</p> Signup and view all the answers

Individuals with a survival advantage are less likely to breed.

<p>False (B)</p> Signup and view all the answers

What occurs over generations as a result of natural selection?

<p>Adaptation</p> Signup and view all the answers

What is the primary goal of selective breeding?

<p>To create a new breed with desirable characteristics (D)</p> Signup and view all the answers

Selective breeding involves choosing individuals with undesirable characteristics to breed together.

<p>False (B)</p> Signup and view all the answers

Name one characteristic that is commonly selected for in domesticated animals through selective breeding.

<p>Coat color</p> Signup and view all the answers

An example of a plant that has been selectively bred in multiple ways is __________.

<p>wild brassica</p> Signup and view all the answers

Which of the following is NOT a benefit of selective breeding in crop plants?

<p>Random genetic mutation (D)</p> Signup and view all the answers

All dog breeds today are descended from multiple distinct species.

<p>False (B)</p> Signup and view all the answers

What must occur over many generations in selective breeding to establish a new breed?

<p>Repeated selection and breeding</p> Signup and view all the answers

Match the following characteristics with their corresponding outcome in selective breeding:

<p>Disease resistance = Food crops Hardiness to weather conditions = Crop yield Better tasting fruits = Plant varieties Unique flower size = Aesthetic appeal</p> Signup and view all the answers

Flashcards

Variation in Biology

The differences in characteristics between individuals of the same species.

Genetic Variation

Differences in features between individuals of the same species caused by differences in their genes.

Continuous Variation

Characteristic where there are many small degrees of difference between individuals, which can be measured on a scale.

Discontinuous Variation

Characteristic where there are distinct differences between individuals, with no 'in-betweens'.

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Phenotypic Variation

The differences in observable traits between individuals of the same species.

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Bell Curve and Continuous Variation

A smooth bell curve typically represents continuous variation on a graph. This shows the distribution of data with a peak where the most frequent characteristics occur and decreases on both sides.

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Step-like Shape and Discontinuous Variation

A 'step-like' shape on a graph typically represents discontinuous variation. This shows distinct, separate categories of data.

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Significance of Variation

The study of variation helps us understand how populations evolve and adapt to their environments.

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Natural Selection

The process where organisms with traits better suited to their environment survive and reproduce more successfully, passing those advantageous traits to their offspring.

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Evolution by Natural Selection

A change in the gene pool of a population over time due to the increased survival and reproduction of individuals with advantageous traits.

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Snail Shell Color Variation

Variations in shell color among snails, where white shells provide camouflage, leading to higher survival rates and increased reproduction of white-shelled snails.

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Mutation

A change in an organism's DNA sequence, which can lead to new traits, some of which may be beneficial for survival.

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Camouflage

The ability of an organism to blend into its environment, making it less visible to predators.

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Xerophytes

Plants that have adaptations to survive in extremely dry environments, like deserts.

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Small leaves in xerophytes

Small, needle-shaped leaves that reduce the surface area for water evaporation.

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Extensive shallow roots in xerophytes

Shallow roots that quickly absorb large amounts of water when it rains.

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Thickened leaves or stems in xerophytes

Thickened leaves or stems that store water efficiently.

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Range of variation in natural selection

Variations within a species due to differences in genes.

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Overproduction in natural selection

Organisms produce more offspring than the environment can support, leading to competition for resources.

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Survival and reproduction in natural selection

Organisms with traits best suited for their environment survive better and reproduce more often.

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Selective breeding

The intentional breeding of organisms with desirable traits to increase the frequency of those traits in future generations.

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How does selective breeding work?

The process of selecting organisms with desirable traits and breeding them together to produce offspring with even more pronounced desirable traits.

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How has selective breeding impacted dogs?

The process of selective breeding has resulted in the diversity of dog breeds we see today, all originating from a single ancestor.

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What are the goals of selective breeding in plants?

Selective breeding in plants aims to improve characteristics such as disease resistance, yield, and taste.

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What is an example of successful plant breeding?

Wild Brassica has been selectively bred to give rise to a variety of vegetables, showcasing the power of this technique.

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How can selective breeding benefit a population?

Selective breeding can introduce new traits into a population, making it more resilient to environmental changes like disease or climate.

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What are some risks associated with selective breeding?

Selective breeding can lead to a reduction in genetic diversity, making the population vulnerable to diseases or environmental changes.

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What is the overall impact of selective breeding?

Selective breeding is a powerful tool for improving desirable traits in organisms, but it is important to consider the potential risks associated with it.

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Variation in a Species

Individuals within a species exhibit differences in traits. These variations can be caused by genetic mutations, environmental factors, or a combination of both.

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What is Natural Selection?

Natural selection is the process by which organisms with traits that make them better adapted to their environment are more likely to survive, reproduce, and pass on those beneficial traits to their offspring.

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How does environmental change impact natural selection?

A change in the environment can cause a shift in which traits are advantageous. For example, a change in food availability can lead to selective pressure that favors organisms with different traits.

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What is Fitness?

The 'fitness' of an organism refers to its ability to survive and reproduce in a given environment. It is not necessarily about being the 'strongest' but rather about being well-suited to the environment.

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How does natural selection lead to evolution?

Over long periods of time, natural selection can lead to the evolution of new species as populations adapt to their environments. This can happen through a gradual accumulation of small changes or through sudden changes caused by mutations or hybridization.

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What is evolution?

Evolution is a gradual process where populations of organisms change over time as a result of natural selection. These changes can be small or large and can take place over thousands or even millions of years.

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What is Antibiotic Resistance?

Antibiotic resistance occurs when bacteria develop the ability to survive and reproduce in the presence of antibiotics. This happens due to mutations in bacterial genes that allow them to resist the effects of the antibiotic.

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Why is antibiotic resistance a problem?

Antibiotic resistance is a serious public health problem because it makes infections harder to treat and can lead to the emergence of 'superbugs' that are resistant to multiple antibiotics.

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Study Notes

Variation in Biology

  • Variation is defined as differences between individuals of the same species.
  • Phenotypic variation is the difference in features between individuals of the same species.
  • Some of these differences are caused by differences in genes, which is genetic variation.
  • Phenotypic variation can be divided into two types depending on how the measurements are grouped.

Types of Variation

  • Continuous Variation: Many small degrees of difference in a characteristic, measured on a scale. Examples include height, mass, and finger length.
  • Discontinuous Variation: Distinct differences in a characteristic, with no in-between values. Examples include blood groups (A, B, AB, O), sex (male or female), and tongue rolling ability.
  • When plotted graphically, continuous variation shows a smooth bell curve, while discontinuous variation forms a step-like shape.

Genetic Variation

  • Examples of genetic variation in humans include blood group and eye color.

Environmental Variation

  • Characteristics are affected by factors such as climate, diet, culture, lifestyle, and accidents.
  • Examples include scarring from an accident, weight gain from poor diet, and speaking a specific language based on where you grew up.

Genetic and Environmental Causes

  • Discontinuous variation is usually caused by genetic variation alone.
  • Continuous variation often results from a combination of genetic and environmental factors.

Mutations

  • Mutations are random genetic changes to DNA.
  • Most mutations have no effect on the phenotype.
  • Occasionally, mutations lead to new alleles creating new phenotypes and may give an individual a survival advantage over other members of the species.
  • Examples include changes in feather colors that could improve mating success.
  • Mutations can be harmful to individuals, exemplified by sickle cell anemia.
  • Mutations can be increased by exposure to ionizing radiation (e.g., X-rays, gamma rays) or certain chemicals.

Adaptive Features

  • Adaptive features are inherited traits that increase an organism's fitness.
  • Fitness is the probability of an organism surviving and reproducing in its environment.
  • Plants have adapted leaves depending on their habitat.

Hydrophytes

  • Plants adapted to extremely wet conditions.
  • Common adaptations include large air spaces in leaves for flotation, small roots, and stomata mainly on the upper epidermis.

Xerophytes

  • Plants adapted to extremely dry conditions.
  • Common adaptations include a thick waxy cuticle, sunken stomata, rolled leaves with stomata on the inside, and extensive shallow roots.
  • Plants in very dry conditions like deserts have small, needle-shaped leaves to minimize water loss.

Natural Selection

  • Individuals with the most beneficial adaptive features are more likely to survive and reproduce.
  • This leads to natural selection as only those individuals are capable of having offspring with similar traits.
  • This is known as the concept of 'survival of the fittest'.

Artificial Selection

  • Humans select individuals with desirable characteristics and breed them together.
  • This process is repeated for successive generations to produce a 'new breed' with specific desired traits.
  • Examples include dog breeds like pugs, and crop plants like cauliflower, broccoli, and kale all evolved from the same original plant.

Natural vs Artificial Selection

  • Natural selection occurs naturally, leading to populations better adapted to their environment.
  • Artificial selection is when humans intervene and control which traits are passed on to the next generation.

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Description

Explore the concepts of variation and natural selection in this quiz. You'll learn about continuous vs. discontinuous variation, examples of genetic variation, and how environmental factors can influence phenotypic traits. Test your knowledge on survival strategies and allele changes in populations.

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