Genetics and Heredity
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Middle School Life Science › Genetics and Heredity
The physical trait, "brown eyes" is best described as:
phenotype
genotype
alleles
gene
Explanation
The answer is "a phenotype."
DNA is the set of instructions for our physical traits. Small sections of DNA that code for a single trait are called genes. Genes can come in 2 different forms called alleles. We represent alleles with both lowercase and uppercase letters. Uppercase and lowercase letters are used to show which alleles are dominant and which are recessive. A dominant (uppercase letter) allele will overpower a recessive allele (lowercase letter).
Our genotype is our genetic code. When we are writing our genotype we show our genetic code by using two alleles because we get one from our mothers and one from our fathers. Our phenotype is our physical traits. If brown eyes are dominant to blue eyes, we will represent brown eyes with a “B” and blue eyes with a “b”. Because we have two alleles, there are 3 different ways we can write a genotype. We can write a genotype as Bb, BB, or bb.
Heterozygous means that a genotype has a dominant allele from one parent and a recessive allele from the other parent. (Bb) Homozygous dominant means that a genotype has two dominant alleles. (BB) homozygous recessive means that a genotype has two recessive alleles. (bb)
Which genetic process is LEAST likely to add a variety of new traits to an individual?
accurate replication
genetic engineering
deletion of DNA
crossover and recombination
Explanation
The answer is "accurate replication."
A genetically diverse population of individuals is more likely to survive than a population of individuals with similar genetic makeup. Variation allows some individuals within a population to adapt to the changing environment and natural selection allows the expression of those beneficial traits to persist. For example, if a population of organisms has the same genetic makeup, it is far less likely to survive disease, drought, or predation than one with genetic variation.
Which of these processes is most important for genetic variation?
meiosis
mitosis
asexual reproduction
cellular respiration
Explanation
The answer is meiosis because that is where "crossover" and recombination of DNA take place in sexual reproduction, increasing genetic variation of offspring.
A genetically diverse population of individuals is more likely to survive than a population of individuals with similar genetic makeup. Variation allows some individuals within a population to adapt to the changing environment and natural selection allows the expression of those beneficial traits to persist. For example, if a population of organisms has the same genetic makeup, it is far less likely to survive disease, drought, or predation than one with genetic variation.
Which of these processes is most important for genetic variation?
meiosis
mitosis
asexual reproduction
cellular respiration
Explanation
The answer is meiosis because that is where "crossover" and recombination of DNA take place in sexual reproduction, increasing genetic variation of offspring.
A genetically diverse population of individuals is more likely to survive than a population of individuals with similar genetic makeup. Variation allows some individuals within a population to adapt to the changing environment and natural selection allows the expression of those beneficial traits to persist. For example, if a population of organisms has the same genetic makeup, it is far less likely to survive disease, drought, or predation than one with genetic variation.
The physical trait, "brown eyes" is best described as:
phenotype
genotype
alleles
gene
Explanation
The answer is "a phenotype."
DNA is the set of instructions for our physical traits. Small sections of DNA that code for a single trait are called genes. Genes can come in 2 different forms called alleles. We represent alleles with both lowercase and uppercase letters. Uppercase and lowercase letters are used to show which alleles are dominant and which are recessive. A dominant (uppercase letter) allele will overpower a recessive allele (lowercase letter).
Our genotype is our genetic code. When we are writing our genotype we show our genetic code by using two alleles because we get one from our mothers and one from our fathers. Our phenotype is our physical traits. If brown eyes are dominant to blue eyes, we will represent brown eyes with a “B” and blue eyes with a “b”. Because we have two alleles, there are 3 different ways we can write a genotype. We can write a genotype as Bb, BB, or bb.
Heterozygous means that a genotype has a dominant allele from one parent and a recessive allele from the other parent. (Bb) Homozygous dominant means that a genotype has two dominant alleles. (BB) homozygous recessive means that a genotype has two recessive alleles. (bb)
Which genetic process is LEAST likely to add a variety of new traits to an individual?
accurate replication
genetic engineering
deletion of DNA
crossover and recombination
Explanation
The answer is "accurate replication."
A genetically diverse population of individuals is more likely to survive than a population of individuals with similar genetic makeup. Variation allows some individuals within a population to adapt to the changing environment and natural selection allows the expression of those beneficial traits to persist. For example, if a population of organisms has the same genetic makeup, it is far less likely to survive disease, drought, or predation than one with genetic variation.
A population of ferns is exposed to the same amount of a toxic chemical and only a few of the mushrooms survive. What is the best explanation for the resistance of some of the mushrooms to the chemical's effects?
the presence of mutations in individual mushrooms
developed in response to the chemical being applied
immunity was transferred from the chemical
resistance was passed down from the top of the food chain
Explanation
The answer is "the presence of mutations in individual mushrooms."
A genetically diverse population of individuals is more likely to survive than a population of individuals with similar genetic makeup. Variation allows some individuals within a population to adapt to the changing environment and natural selection allows the expression of those beneficial traits to persist. For example, if a population of organisms has the same genetic makeup, it is far less likely to survive disease, drought, or predation than one with genetic variation.
A population of ferns is exposed to the same amount of a toxic chemical and only a few of the mushrooms survive. What is the best explanation for the resistance of some of the mushrooms to the chemical's effects?
the presence of mutations in individual mushrooms
developed in response to the chemical being applied
immunity was transferred from the chemical
resistance was passed down from the top of the food chain
Explanation
The answer is "the presence of mutations in individual mushrooms."
A genetically diverse population of individuals is more likely to survive than a population of individuals with similar genetic makeup. Variation allows some individuals within a population to adapt to the changing environment and natural selection allows the expression of those beneficial traits to persist. For example, if a population of organisms has the same genetic makeup, it is far less likely to survive disease, drought, or predation than one with genetic variation.
Imagine there are 3 populations of snow hares. Snow hares have different colored fur ranging from white to brown. White snow hares can hide from predators more easily in the snow, and light brown snow hares can hide more easily in the grass and brush when the snow melts. Which of these populations of snow hares is most likely to survive this a winter with constantly changing weather and unpredictable snow?
Population 1: All the snow hares are completely white
Population 2: Most of the snow hares are completely white, but some of them have brown splotches.
Population 3: There are many snow hares of all different colors from completely white to completely brown.
population 3
population 2
population 1
not enough information
Explanation
The answer is population 3 because it has the most genetic variation.
A genetically diverse population of individuals is more likely to survive than a population of individuals with similar genetic makeup. Variation allows some individuals within a population to adapt to the changing environment and natural selection allows the expression of those beneficial traits to persist. For example, if a population of organisms has the same genetic makeup, it is far less likely to survive disease, drought, or predation than one with genetic variation.
Imagine there are 3 populations of snow hares. Snow hares have different colored fur ranging from white to brown. White snow hares can hide from predators more easily in the snow, and light brown snow hares can hide more easily in the grass and brush when the snow melts. Which of these populations of snow hares is most likely to survive this a winter with constantly changing weather and unpredictable snow?
Population 1: All the snow hares are completely white
Population 2: Most of the snow hares are completely white, but some of them have brown splotches.
Population 3: There are many snow hares of all different colors from completely white to completely brown.
population 3
population 2
population 1
not enough information
Explanation
The answer is population 3 because it has the most genetic variation.
A genetically diverse population of individuals is more likely to survive than a population of individuals with similar genetic makeup. Variation allows some individuals within a population to adapt to the changing environment and natural selection allows the expression of those beneficial traits to persist. For example, if a population of organisms has the same genetic makeup, it is far less likely to survive disease, drought, or predation than one with genetic variation.