8 Most Useful Bill Nye Videos To Watch

-Even if you are in college.

Bill Nye the Science Guy hasn’t produced new episodes since the end of Season 5 in 1998, but the show’s namesake host remains active in the promotion of science – and many of his videos remain outstanding content to watch even if you’re in College (or beyond).

Here at Biology Junction, our focus is on our own namesake subject, and that’s what this list focuses on – but for those of you who came here for a more general list, we’ve also included a few non-Biology videos down at the bottom. These videos are helpful regardless of what type of science you’re interested in, so everyone should take a look at them.

How We Chose These Videos

What good is a list without an explanation of how we made it? It wouldn’t be good science if we just threw it up here! Truth is, though, creating this list wasn’t very hard. First, we narrowed our list of sources to the best selections of Bill Nye videos – his classic show and the more-recent Greatest Discoveries series.

Next, we considered how useful each topic is to know. For students studying biology, it does no good to dive into topics more advanced than you’re ready for. Fortunately, most of Bill Nye’s videos are accessible even to beginners and provide a strong foundation for the topic. This ended up being a minor concern, but we were determined to go through the process.

Finally, we checked for the availability of videos. It doesn’t help to be told to watch a video if you can’t find it. A simple search should be enough to locate any of the videos on this list. If that fails, you should be able to get them from your library or preferred streaming service. We had a preference for videos that are freely available since budgets can be tight in college, but that didn’t significantly impact this list.

For our non-Biology videos, we used a similar process. Instead of emphasizing Biology, though, we decided to focus on the foundations of science and the information that’s most useful for everyone to know.

The Best Biology Videos From Bill Nye

Here are our top choices for Biology videos.

1: Biodiversity (S1 E9)

Biodiversity is the 9th episode of Bill Nye the Science Guy, and while it’s not the first to feature a Biology topic, we think it’s easily one of the most important episodes. This video focuses on more than just where things live – it also explains the concept of ecosystems and how important it is to have a variety of living things in each area.

Fish in the habitat

Arguably the most important lesson of this episode is understanding that ecosystems are far more complex than figuring out which living things eat each other. Each part of an ecosystem affects all of the other parts. That’s why we have to be so careful when introducing plants or animals to new habitats – if the ecosystem isn’t ready to handle it, the whole thing could collapse.

A second lesson to focus on is how ecosystems can vary in size – and, in many cases, overlap each other. The Great Barrier Reef has its own ecosystem, but it’s part of the larger Pacific Ocean – and from there, it ultimately affects all life on the planet (even if the impact isn’t obvious).

Understanding biodiversity is critical to understanding biology as a whole. Life does not exist in a vacuum – not unless we put it there, anyway. Environments affect life and vice versa, and if you want to understand why something is the way it is, you have to look at the bigger picture.

2: Cells (S1 E17)

cells

Cells are a fundamental component of life – and even if you think you understand them, it’s good to get a refresher on the topic before you start your studies. The main reason for this is that when we say something “affects an organ”, what we mean is “it affects certain cells of the organ in a particular way”.

For example, if you want to understand why too much alcohol can hurt the liver, you need to look at its impact on the cells of the liver. If you want to heal that liver when you’re done, you have to figure out what will encourage the cells to do that. Cells are the ultimate “micro” topic in biology, making the Bill Nye cells video easily one of the most important episodes for biologists to watch.

3: Food Web (S2 E6)

It’s hard to talk about biology without eventually talking about food – but how things get their food is a little more complicated. Only watch this video after you’ve watched Biodiversity, because that video provides some important groundwork for this topic.

The short version is that a food web describes how each part of an ecosystem gets its food. Ultimately, each living thing gets food either from other living things (like insects, plants, or rodents) or from the sun. Every living creature is ultimately dependent on plants – who, let’s not forget, are often nourished by the uneaten bodies of dead creatures.

(If you’re having flashbacks to a certain Disney movie about a young lion, there’s a reason for that – the Circle of Life, where living things depend on each other, is quite real.) Watch Food Web

4: Plants (S3 E3)

Given how important plants are to the previous video, now’s a good time to get a refresher on what they are, how they work, and what sort of impact they have on our lives. The crazy thing is how plants can synthesize their own food as long as they have sunlight, water, and carbon dioxide – though healthy soil and a few other nutrients certainly help.

plant

Plants are also important for their impact on other aspects of Biology. For example, many medicines are made from plants or plant by-products and affect certain living things in specific ways. Once we understand how something works, we can start figuring out the best way to make use of it.

This is particularly helpful if you’re looking for a job with biology. Most of your work will likely involve seeing how various inputs (types of food, situations, etc.) affect living things, and plants will be a part of that. Studying life alone is a limited topic – but there are endless possibilities when studying the way things affect life.

5: Populations (S3 E19)

Populations are a group of similar living things living in a set area. We often refer to the population of the human race, but we may also talk about the population of a specific city, voting district, or another region.

sunset with population

In biology, the most important thing is understanding the populations of other living things, how they’ve changed over time, and what’s caused them to do so. As you learned in videos like Biodiversity and Food Web, living things all affect each other – and a sudden rise or drop in one population will ripple across the ecosystem and begin affecting other creatures.

There may not be as many fancy names or scientific terms here, but it’s still worth watching this video to ensure you have a good grasp of the fundamentals of biology.

6: Biology – Greatest Discoveries

Finally, Bill Nye’s Greatest Discoveries video on Biology rounds out the best videos on this topic with a look at 13 of the most important discoveries in biology. This includes a discussion on the discovery and impact of:

  • Microorganisms like bacteria, blood cells, and sperm
  • The Cell Nucleus that functions at the center point of most cells
  • Archaea, microorganisms that lack a cell nucleus but aren’t quite like bacteria
  • Cell Division, the process of growth and, in many ways, life itself
  • Sex Cells and how they differ from most other types of cells
  • Cell Differentiation and how different types of cells are made
  • Mitochondria, which are separate from cells but provide a critical function for metabolizing chemicals
  • The Krebs Cycle, which is how protein, fats, and sugars are turned into energy
  • Neurotransmission, which centralizes the body’s ability to control itself
  • Hormones, which are far more complicated than teenage urges
  • Photosynthesis, a process where light is turned into chemical energy
  • Ecosystems, a quick look back at larger ecological units
  • Tropical Biodiversity, or why warm and sunny places tend to have a much greater variety of life

Together, all of these are important for biologists to know.

The Best Overall Science Videos From Bill Nye

Whether or not you’re focused on biology, these videos are helpful for improving your overall understanding of science and are worth watching at any age.

1: Pseudoscience (S4 E9)

Many things that sound like science but aren’t. These things are often called pseudoscience, and learning how to recognize them is a valuable skill for any scientist. Fortunately, the entire topic can be brought down to a few simple principles.

First, science involves testing claims and ideas. If somebody says something can’t be tested, then it’s not within the realm of science and shouldn’t be treated as such. In those cases, it’s okay to say “perhaps we’ll never know for sure”.

Second, extraordinary claims require extraordinary proof. In other words, the more important your claim is, the more you need to support it with verifiable evidence. As the person making a claim, it is your job to provide corresponding proof. It is not the job of others to demonstrate that you’re right.

Furthermore, your results should be reproducible. Proper science only happens when someone tries to prove you wrong – fairly, of course – and fails to do so. If you repeat an experiment and keep getting results, you don’t have any answers – just more questions to ask.

Finally, you should learn critical thinking. This graphic is especially helpful for that and provides many questions that help you uncover the truth. For example, when presented with a claim, you may want to figure out who benefits from it, what the best/worst case scenarios of it are, where it might be a problem or solution, what might make it unacceptable, why people might need it, and how to approach it safely.

In many cases, purveyors of pseudoscience are simply looking to profit from your ignorance. As a scientist, it is your duty to see past things like that and uncover the truth. Watch Pseudoscience now.

2: Measurement (S5 E17)

Coming in as one of the last episodes ever aired, Measurement is something that honestly should have been one of the first videos they made. Measuring things is critical to the foundations of science as a whole. Proper measurements provide objective, verifiable information using a common set of standards, and it’s impossible to overstate how important this is.

There are a few important things to learn from this video, Measurement.

First, there are many ways of measuring things. You can measure units (members of a population), dimensions (the size of something), time (how long it takes something to happen), effects (what happens), and many other topics.

Second, you’ll learn why things should be measured. It’s not just to expand the amount of information we have, though that’s valuable in and of itself. Instead, measurements help us understand what’s different about two subjects so we can proceed to uncover why and how that difference occurred.

Taken far enough, this can lead to discoveries, such as finding that one person in a neighborhood didn’t get sick because they ate a particular herb.

Measurements are almost never a focus in and of themselves – but they’re a vital part of most scientific activities. If you want to be a scientist, then you’re almost certainly going to do a lot of measurements over the course of your career. That makes this innocent-sounding video one of the most helpful episodes of Bill Nye.

Ecology Quiz

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Ecology
  1. Which two biomes are the most similar with regard to rainfall?
    tundra & taiga
    tundra & desert
    rain forest & savanna
    temperate forest & prairie
  2. Which biome is characterized by a layer of permafrost?
    taiga
    savanna
    chaparral
    tundra
  3. Biodiversity is greatest in which biome?
    taiga
    polar
    rain forest
    savanna
  4. The eastern portion of the United States is dominated by what biome?
    temperate forest
    desert
    taiga
    prairie
  5. In which biome of Africa would you find lions, giraffes, and elephants?
    savanna
    chaparral
    desert
    tropical rain forest
  6. All the different species of an ecoystem are referred to as the:
    biome
    community
    population
    abiotic factors
  7. Which of the following would represent an ecosystem?
    A lake
    A fish tank
    A prairie
    all of these
  8. All the nonliving parts of an ecosystem are referred to as:
    the community
    biotic factors
    abiotic factors
    biomes
  9. Which of the following would be a biotic factor in an ecosystem?
    bacteria
    soil
    temperature
    rainfall
  10. The types and numbers of species in a given area is most greatly determined by the area’s:
    biotic factors
    precipitation
    climate
    biodiversity

Score =
Correct answers:

Evolution Quiz

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Evolution
    1. In biological terms, what is a species? a group of organisms that are similar in form and structure
      a group of organisms that can interbreed
      a group of organisms that share common features
      a group of organisms that have live in the same habitat
    2. What is the Scala Naturae? an idea proposed by Darwin that suggests that all organisms share a common ancestor
      an idea proposed by Plato that suggests organisms are all evolving toward an ideal form
      an idea proposed by Aristotle that suggests that all organisms fit into an orderly scheme
      an idea proposed by Wallace that suggests that organisms change over time
    3. Creationism is not accepted as a valid scientific theory because: it violates the scientific principle of natural causality
      it doesn’t offer a model to explain the diversity of life on earth
      it cannot be disproven
      all of these

birds

    1. The picture of the finches is used to illustrate: phylogeny of finches
      change over time
      specialization of beaks for different diets
      natural selection
    2. Which of the following was not an observation made by Darwin on his voyages: penguins use wings to paddle instead of fly
      snakes have rudimentary hind limbs
      the earth is very old
      islands had species that did not exist on the mainland

bones

    1. The image illustrates: vestigial structures
      homologous structures
      the fossil record
      natural selection
    2. Which of the following is an example of artificial selection: a panda’s thumb
      the breeding of dogs
      the galapagos finches
      a giraffe’s neck
    3. According to the theory of evolution by natural selection, which of the following is true: random mating is necessary for evolution to occur
      variation does not exist between members of the same species
      populations will change to better fit their environment
      individuals will adapt to their environment
    4. Which of the following are assumptions made with regards to the Theory of Evolution by Natural selection organisms compete with each other to survive
      variations exist among organisms
      not all organisms that are born survive to reproduce
      all of these

whale

    1. The image illustrates which of the following: artificial selection
      acquired characteristics
      homologous structures
      vestigial structures
    2. A panda’s thumb is considered an evolutionary contrivance because: it is assembled from wrist bones, and imperfect
      it is perfectly structured to grab leaves
      it is an structure that has no use
      none of these
    3. Which of the following outcomes would you predict for a population of bacteria exposed to a new antibiotic. over many generations, the bacteria would become resistant to the antibiotic
      over a few generations, the bacteria would evolve into Archaebacteria
      over a few generations, the bacteria would become extinct
      over many generations, the bacteria would become more susceptible to the antibiotic
    4. Which of the following is an example of convergent evolution: whales and sharks have similar body designs
      bees and hummingbirds have similar body designs
      bats and birds have similar body designs
      all of these
    5. Why is evolution called the “unifying theory of biology” because it explains the diversity of life on the planet
      because it serves as a model to predict how organisms will change
      it serves as a model to interpret relationships between organisms on the planet
      all of these

moths

  1. The image illustrates how peppered moths are related to other moths
    how peppered moths adapted to a changing environment
    how peppered moths became extinct
    how peppered moths became two species

Check Answers

Genetics Quiz

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Chromosomes & Genetics

1. A human being has _____ autosomes and ______ sex chromosomes
23, 1
22 pairs, 1 pair
23, 23
2, 2

2. A section of chromosomes that codes for a trait can be called a(n):
nucleotide
base-pair
gene
nucleus

3. Somatic cells of a human have ____ chromosomes and are called ____
10, haploid
92, diploid
23, haploid
46, diploid

4. A person who receives an extra chromosome, could have:
Heightened intelligence
Down Syndrome
Red eyes
Polygenic traits

5. Each chromosome consists of two identical:
genes
nuclei
chromatids
bases

6. If a person receives an X and a Y chromosome, that person is:
female
male
red eyed
mentally challenged

7. Two alleles for pea plant height are designated T (tall) and t (dwarf). These alleles are found on:
genes
sex chromosomes
ribosomes
homologous chromosomes

8. An animal has 40 chromosomes in its gametes, how many chromosomes would you expect to find in this animal’s brain cells?
1
20
40
80

9. A picture of a person’s chromosomes is called a(n):
karyotype
syndrome
chromatin
fingerprint

10. During which phase of mitosis is DNA replicated?
interphase
prophase
anaphase
telophase

Score =
Correct answers:

Genetics Practice Test

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Genetics Practice Test

 

 

Multiple Choice
Identify the choice that best completes the statement or answers the question.
 1.
Mendel prevented self-pollination of his plants by
a.
growing only one kind of plant.
b.
preventing crossing-over.
c.
removing the anthers of the plants.
d.
removing the stigmas of the plants.
 2.
The “father” of genetics was
a.
T. A. Knight.
c.
Gregor Mendel.
b.
Hans Krebs.
d.
None of the above
 3.
Mendel obtained his P generation by allowing the plants to
a.
self-pollinate.
c.
assort independently.
b.
cross-pollinate.
d.
segregate.
 4.
What is the probability that the offspring of a homozygous dominant individual and a homozygous recessive individual will exhibit the dominant phenotype?
a.
0.25
c.
0.66
b.
0.5
d.
1.0
 5.
True-breeding pea plants always
a.
are pollinated by hand.
b.
produce offspring each of which can have multiple forms of a trait.
c.
produce offspring each of which can have only one form of a trait.
d.
are heterozygous.
 6.
The first filial (F1) generation is the result of
a.
cross-pollination among parents and the next generation.
b.
crosses between individuals of the parental generation.
c.
crosses between the offspring of a parental cross.
d.
self-fertilization between parental stock.
 7.
Which of the following is the designation for Mendel’s original pure strains of plants?
a.
P
c.
F1
b.
P1
d.
F2
 8.
F2 : F1 ::
a.
P : F1
c.
F1 : P
b.
F1 : F2
d.
dominant trait : recessive trait
 9.
The passing of traits from parents to offspring is called
a.
genetics.
c.
development.
b.
heredity.
d.
maturation.
 10.
A genetic trait that appears in every generation of offspring is called
a.
dominant.
c.
recessive.
b.
phenotypic.
d.
superior.
 11.
homozygous : heterozygous ::
a.
heterozygous : Bb
c.
BB : Bb
b.
probability : predicting chances
d.
homozygous : BB
 12.
Mendel’s finding that the inheritance of one trait had no effect on the inheritance of another became known as the
a.
law of dominance.
b.
law of universal inheritance.
c.
law of separate convenience.
d.
law of independent assortment.
 13.
To describe how traits can disappear and reappear in a certain pattern from generation to generation, Mendel proposed
a.
the law of independent assortment.
b.
the law of segregation.
c.
the law of genotypes.
d.
that the F2 generation will produce only purple flowers.
 14.
The law of segregation explains that
a.
alleles of a gene separate from each other during meiosis.
b.
different alleles of a gene can never be found in the same organism.
c.
each gene of an organism ends up in a different gamete.
d.
each gene is found on a different molecule of DNA.
 15.
When Mendel crossed pea plants that differed in two characteristics, such as flower color and plant height,
a.
these experiments led to his law of segregation.
b.
he found that the inheritance of one trait did not influence the inheritance of the other trait.
c.
he found that the inheritance of one trait influenced the inheritance of the other trait.
d.
these experiments were considered failures because the importance of his work was not recognized.
 16.
The phenotype of an organism
a.
represents its genetic composition.
b.
reflects all the traits that are actually expressed.
c.
occurs only in dominant pure organisms.
d.
cannot be seen.
 17.
If an individual has two recessive alleles for the same trait, the individual is said to be
a.
homozygous for the trait.
b.
haploid for the trait.
c.
heterozygous for the trait.
d.
mutated.
 18.
An individual heterozygous for a trait and an individual homozygous recessive for the trait are crossed and produce many offspring. These offspring are likely to be
a.
all the same genotype.
b.
of two different phenotypes.
c.
of three different phenotypes.
d.
all the same phenotype.
 19.
Tallness (T) is dominant over shortness (t) in pea plants. Which of the following represents the genotype of a pea plant that is heterozygous for tallness?
a.
T
c.
Tt
b.
TT
d.
tt

In humans, having freckles (F) is dominant over not having freckles (f). The inheritance of these traits can be studied using a Punnett square similar to the one shown below.

nar001-1.jpg

 20.
Refer to the illustration above. The genotype represented in box 1 in the Punnett square would
a.
be homozygous for freckles.
b.
have an extra freckles chromosome.
c.
be heterozygous for freckles.
d.
have freckles chromosomes.
 21.
Refer to the illustration above. The genotype in box 3 of the Punnett square is
a.
FF.
c.
ff.
b.
Ff.
d.
None of the above
 22.
A trait that occurs in 450 individuals out of a total of 1,800 individuals occurs with a probability of
a.
0.04.
c.
0.50.
b.
0.25.
d.
0.75.
 23.
How many different phenotypes can be produced by a pair of codominant alleles?
a.
1
c.
3
b.
2
d.
4
nar002-1.jpg
 24.
Refer to the illustration above. The phenotype represented by box 1 is
a.
green, inflated.
c.
yellow, inflated.
b.
green, constricted.
d.
yellow, constricted.
 25.
Refer to the illustration above. The genotype represented by box 2 is
a.
GgIi.
c.
GI.
b.
GGIi.
d.
Gi.
 26.
2,000 yellow seeds : 8,000 total seeds ::
a.
1 : 6
c.
1 : 3
b.
1 : 8
d.
1 : 4

In rabbits, black fur (B) is dominant over brown fur (b). Consider the following cross between two rabbits.

nar003-1.jpg

 27.
Refer to the illustration above. The device shown, which is used to determine the probable outcome of genetic crosses, is called a
a.
Mendelian box.
c.
genetic graph.
b.
Punnett square.
d.
phenotypic paradox.
 28.
Refer to the illustration above. Both of the parents in the cross are
a.
black.
b.
brown.
c.
homozygous dominant.
d.
homozygous recessive.
 29.
Refer to the illustration above. The phenotype of the offspring indicated by box 3 would be
a.
brown.
b.
black.
c.
a mixture of brown and black.
d.
The phenotype cannot be determined.
 30.
Refer to the illustration above. The genotypic ratio of the F1 generation would be
a.
1:1.
c.
1:3.
b.
3:1.
d.
1:2:1.
 31.
What is the expected genotypic ratio resulting from a homozygous dominant ´ heterozygous monohybrid cross?
a.
1:0
c.
1:2:1
b.
1:1
d.
1:3:1
 32.
What fraction of the offspring resulting from a heterozygous ´ heterozygous dihybrid cross are homozygous recessive for both traits?
a.
9/16
c.
3/16
b.
1/4
d.
1/16
 33.
What is the expected genotypic ratio resulting from a heterozygous ´ heterozygous monohybrid cross?
a.
1:2:1
c.
1:2
b.
1:3:1
d.
1:0
 34.
What is the expected phenotypic ratio resulting from a homozygous dominant ´ heterozygous monohybrid cross?
a.
1:3:1
c.
2:1
b.
1:2:1
d.
1:0
nar004-1.jpg
 35.
Refer to the illustration above. The phenotype represented by box 1 is
a.
round, yellow.
c.
wrinkled, yellow.
b.
round, green.
d.
wrinkled, green.
 36.
Refer to the illustration above. The genotype represented by box 2 is
a.
RRYY.
c.
RrYy.
b.
RrYY.
d.
rrYy.
 37.
Refer to the illustration above. Which of the following boxes represents the same phenotype as box 7?
a.
3
c.
5
b.
4
d.
6
 38.
An organism that has inherited two of the same alleles of a gene from its parents is called
a.
hereditary.
c.
homozygous.
b.
heterozygous.
d.
a mutation.
 39.
In pea plants, yellow seeds are dominant over green seeds. What would be the expected genotype ratio in a cross between a plant with green seeds and a plant that is heterozygous for seed color?
a.
1:3
c.
4:1
b.
1:2:1
d.
1:1
 40.
codominance : both traits are displayed ::
a.
probability : crosses
b.
heterozygous : alleles are the same
c.
homozygous : alleles are the same
d.
Punnett square : chromosomes combine
 41.
The difference between a monohybrid cross and a dihybrid cross is that
a.
monohybrid crosses involve traits for which only one allele exists, while dihybrid traits involve two alleles.
b.
monohybrid crosses involve self-pollination, while dihybrid crosses involve cross-pollination.
c.
monohybrid crosses involve one trait; dihybrid crosses involve two traits.
d.
dihybrid crosses require two Punnett squares; monohybrid crosses need only one.
 42.
What fraction of the offspring resulting from a heterozygous ´ heterozygous dihybrid cross are heterozygous for both traits?
a.
9/16
c.
3/16
b.
1/4
d.
1/16
 43.
A cross of two individuals for a single contrasting trait is called
a.
monohybrid.
c.
dominant.
b.
dihybrid.
d.
codominant.
 

Completion
Complete each statement.
 44.
The transferring of pollen between plants is called ____________________.

 45.
Mendel produced true-breeding strains of pea plants through the process of ____________________.

 46.
When two members of the F1 generation are allowed to breed with each other, the offspring are referred to as the ____________________ generation.

 47.
In heterozygous individuals, only the ____________________ allele achieves expression.

 48.
The statement that the members of each pair of alleles separate when gametes are formed is known as the _________________________.

 49.
Different forms of a particular gene, which Mendel called factors, are now called ____________________.

 50.
The cellular process that results in the segregation of Mendel’s factors is ____________________.

 51.
The portion of a DNA molecule containing the coded instructions that result in a particular characteristic of an organism is called a(n) ____________________.

 52.
An organism’s ____________________ refers to the set of alleles it has inherited.

 53.
The likelihood that a specific event will occur is called ____________________.

 54.

co054-1.jpg

Refer to the illustration above. The box labeled “X” represents the phenotype ____________________.

 55.
A fractional probability of 1/2 is the same as a decimal probability of ____________________.

In pea plants, tallness (T) is dominant over shortness (t). Crosses between plants with these traits can be analyzed using a Punnett square similar to the one shown below.

nar005-1.jpg

 56.
Refer to the illustration above. The parents shown in the Punnett square are likely to have offspring with a genotype ratio of ____________________.

 57.
Refer to the illustration above. Box 2 and box ____________________ in the Punnett square represent plants that would be heterozygous for tallness.

 58.
Refer to the illustration above. The phenotype of the plant that would be represented in box 4 of the Punnett square would be ____________________.

 59.
Refer to the illustration above. The genotype of both parents shown in the Punnett square above is ____________________.

 60.
A situation in which both alleles for a trait are expressed in a heterozygous offspring is called ____________________.

 61.
A pattern of heredity in which a heterozygous individual has a phenotype that is intermediate between the phenotypes of its two homozygous parents is called _________________________.

 62.
A table used to determine and diagram the results of a genetic cross is called a ____________________.

 63.
In genetics, lowercase letters are usually used to indicate ____________________.

 

Problem
 64.
In tomato plants, tallness is dominant over dwarfness and hairy stems are dominant over hairless stems. True-breeding (homozygous) plants that are tall and have hairy stems are available. True-breeding (homozygous) plants that are dwarf and have hairless stems are also available. Design an experiment to determine whether the genes for height and hairiness of stem are on the same or different chromosomes. Explain how you will be able to determine from the results whether the genes are on the same chromosome or different chromosomes, and whether they are close to each other or far apart if they are on the same chromosome. Write your answer in the space below.

 65.

A scientist crossed true-breeding tall and hairy-stemmed tomato plants with true-breeding dwarf and hairless-stemmed tomato plants. He found that all of the F1 plants produced as a result of this cross were tall and hairy-stemmed. He then allowed the F1 plants to pollinate each other and obtained 1000 F2 plants. Of these 1000 F2 plants, he observed the following numbers of four different phenotypes:

557 tall and hairy-stemmed plants192 dwarf and hairy-stemmed plants
180 tall and hairless-stemmed plants71 dwarf and hairless-stemmed plants

Write your answers to the following in the space below or on a separate sheet of paper.

a.      Which height characteristic is dominant, tallness or dwarfness?
b.      Which stem characteristic is dominant, hairiness or hairlessness?
c.      What are the genotypes of the original, true-breeding parents? (Be sure to indicate what the symbols you use stand for.)
d.      What are the genotypes of the F1 hybrid plants? (Be sure to indicate what the symbols you use stand for.)
e.      What are the genotypes of the four types of plants found in the F2 generation? (Be sure to indicate what the symbols you use stand for.)
f.      What were the expected numbers of plants of each type in the F2 generation? (Round off to the nearest whole numbers.)
g.      Why did the observed numbers of plants of each type in the F2 generation differ from the expected?
h.      How could this experiment have been changed to obtain numbers of plants of each type in the F2 generation that were closer to the expected numbers?

 

Essay
 66.
How might you go about determining the genotype of a red-flowering plant where red is dominant over white? Write your answer in the space below.

 67.
Describe pollination in pea plants. Write your answer in the space below.

 68.
In what ways did Mendel’s methods help ensure his success in unraveling the mechanics of heredity? Write your answer in the space below.

 69.
What conclusions did Gregor Mendel reach based on his observations of pea plants? Write your answer in the space below.

 70.
Describe Mendel’s observation regarding independent assortment. Write your answer in the space below.

 71.
What are three ways to express the probability of an event that occurs 500 times out of 2,000 total trials? Write your answer in the space below.

 72.
Describe how genotype and phenotype are related, and give an example. Write your answer in the space below.

 73.
Explain what is meant by homozygous and heterozygous, and give an example of each. Write your answer in the space below.

 74.
All of the offspring resulting from a cross between a red snapdragon and a white snapdragon are pink. What is a possible explanation for this? Write your answer in the space below.

 

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