Unit 4 (Week 13 Patterns of Inheritance) Flashcards

Question

What refers to a trait that is masked by the presence of a dominant trait in a heterozygote?

Answer 1

Recessive Tall stems and purple flowers are examples of dominant traits; dwarf stems and white flowers are examples of recessive traits. In this case, we say that tall is dominant over dwarf, and purple is dominant over white.

Answer 2

A gene. At the molecular level, a gene is an organized unit of base sequences in a DNA strand that can transcribed into RNA and ultimately results in the formation of a functional product.

Answer 3

A term coined by the Danish botanist Wilhelm Johannsen in 1909. Comes from the Greek word, genos, meaning birth.

Answer 4

Mendel postulated that every individual carries two genes for a given character and that the gene for each character in his pea plants exists in two variant forms, which we now call alleles.

Answer 5

3:1 ratio. How did Mendel interpret this ratio? He concluded that each F1 plant carried two versions (alleles) of a gene affecting height (or another character) and that the two alleles carried by such an F1 plant separate, or segregate, from each other during the process that gives rise to gametes. Therefore, each sperm or egg carried only one allele.

Answer 6

Mendel's law of segregation

Answer 7

The ratio of alleles (T to t) is 1:1. The reason why the phenotypic ratio is 3:1 is because T is dominant to t.

Answer 8

The genotype. [Use Picture Mendel's Analysis] TT and tt are the genotypes of the P generation, and Tt is the genotype of the F1 generation. In the P generation, both parents are true-breeding plants, which means that each has identical copies of the allele of the gene for height.

Answer 9

Homozygous In the specific cross we are considering, the tall plant (TT) is homozygous for T, and the dwarf plant (tt) is homozygous for t. Heterozygous Plants of the F1 generation are heterozygous, with the genotype Tt, because every individual carries one copy of the tall allele (T) and one copy of the dwarf allele (t). The F2 generation includes both homozygous individuals (homozygotes) and heterozygous individuals (heterozygotes).

Answer 10

Phenotype. Although the F1 offspring are heterozygous (Tt), they are phenotypically tall because each of them has a copy of the dominant tall allele. In contrast, the F2 plants display both phenotypes in a ratio of 3:1.

Answer 11

A Punnett square, developed by British geneticist Reginald Punnett 1. Write down the genotypes of both parents. In this example, a heterozygous tall plant is crossed to another heterozygous tall plant. The plant providing the pollen is considered the male parent and the plant providing the eggs, the female parent. (In self-pollination, a single individual produces both types of gametes.) Male parent: Tt Female parent: Tt 2. Write down the possible gametes that each parent can make. Remember the law of segregation tells us that a gamete contains only one copy of each allele. Male gametes: T or t Female gametes: T or t 3. Create an empty Punnett square. The number of columns equals the number of male gametes, and the number of rows equals the number of female gametes. Our example has two rows and two columns. Place the male gametes across the top of the Punnett square and the female gametes along the side. (Outside the box) Step 4. Fill in the possible genotypes of the offspring by combining the alleles of the gametes in the empty boxes. Step 5. Determine the relative proportions of genotypes and phenotypes of the offspring. The genotypes are obtained directly from the Punnett square. In this example, the genotype ratio is 1 TT : 2 Tt : 1 tt. To determine the phenotypes, you must know which allele is dominant. For plant height, T (tall) is dominant to t (dwarf). The genotypes TT and Tt are tall, whereas the genotype tt is dwarf. Therefore, our Punnett square shows us that the phenotype ratio is expected to be 3 tall : 1 dwarf.

Answer 12

1. It is homozygous for the recessive allele. In this example, a plant that is dwarfed in height, has a genotype of tt which means it is homozygous for the recessive allele. 2. An individual with a dominant phenotype may be either homozygous or heterozygous—a tall pea plant may have the genotype TT or Tt.

Answer 13

Mendel devised a method called a testcross to address this question. In a testcross, the researcher crosses the individual of interest to a homozygous recessive individual and observes the phenotypes of the offspring. Essentially, a cross to determine if an individual with a dominant phenotype is a homozygote or a heterozygote.

Answer 14

The genotype was Pp. To produce white offspring, which are pp, the original plant had to have at least one copy of the p allele. Because it had purple flowers, it also had to have one copy of the P allele. So, its genotype must have been Pp.

Answer 15

Two-factor cross

Answer 16

If alleles of genes are linked, we cannot have any new combinations meaning that the Punnett square would be: YR yr for the sperm YR yr for the eggs YYRR, YyRr, YyRr, and yyrr is the result of the Punnett square. Yellow seeds would always be round and wrinkled seeds would always be green with a 3:1 ratio. Since these alleles of genes are linked, new combinations cannot be created. This hypothesis was proven incorrect a one point, but there are cases where genes are expressed in pairs therefore creating a link.

Answer 17

Independent assortment allows for more combinations of alleles in genes independent of any linkage. If the two genes are linked, the F1 plants could produce gametes that are only YR or yr. These gametes would combine to produce offspring with the genotypes YYRR (yellow, round), YyRr (yellow, round), and yyrr (green, wrinkled). The ratio of phenotypes would be 3 yellow, round to 1 green, wrinkled. Every F2 plant would be phenotypically like one P-generation plant or the other. None would display a new combination of the parental traits. However, if the alleles assorted independently, the F2 generation would have a wider range of genotypes and phenotypes. In this case, the columns and rows will have more combinations since YR and yr are not linked alleles in genes. The example in the book went from YR and yr for both eggs and sperm to TY, Yr, yR, and yr for both eggs and sperm. In this case, each F1 parent produces four kinds of gametes—YR, Yr, yR, and yr—instead of two, so the square is constructed with four rows on each side and shows 16 possible genotypes. The F2 generation includes plants with yellow, round seeds; yellow, wrinkled seeds; green, round seeds; and green, wrinkled seeds, in a ratio of 9:3:3:1.

Answer 18

Mendel's law of independent assostment

Answer 19

August Weismann and Karl Nageli in 1883. This idea challenged other researchers to identify the genetic material. Several scientists, including German biologists Eduard Strasburger and Walther Flemming, observed dividing cells under the microscope and suggested that the chromosomes are the carriers of the genetic material. As we now know, the genetic material is the DNA within chromosomes.

Answer 20

Chromosome Theory of Inheritance 1. Chromosomes contain DNA, which is the genetic material. Genes are found within the chromosomes. 2. Chromosomes are replicated and passed from parent to offspring. They are also passed from cell to cell during the development of a multicellular organism. 3. The nucleus of a diploid cell contains two sets of chromosomes, which are found in homologous pairs. The maternal and paternal sets of homologous chromosomes are functionally equivalent; each set carries a full complement of genes. 4. At meiosis, one member of each chromosome pair segregates into one daughter nucleus, and its homolog segregates into the other daughter nucleus. During the formation of haploid Page 356cells, the members of different chromosome pairs segregate independently of each other. 5. Gametes are haploid cells that combine to form a diploid cell during fertilization, with each gamete transmitting one set of chromosomes to the offspring.

Answer 21

Locus or loci for plural

Answer 22

Yes, because they are the same in structure just not in function.

Answer 23

Two homologous chromosomes prior to DNA replication. When a cell prepares to divide, the homologs replicate to produce pairs of sister chromatids. Each chromatid carries a copy of the allele found on the original homolog, either T or t. During meiosis I, the homologs, each consisting of two sister chromatids, pair up and then segregate into two daughter cells. One of these cells has two copies of the T allele, and the other has two copies of the t allele. The sister chromatids separate during meiosis II, which produces four haploid cells. The end result of meiosis is that each haploid cell has a copy of just one of the two original homologs. Two of the cells have a chromosome carrying the T allele, and the other two have a chromosome carrying the t allele at the same locus.

Answer 24

The alleles for seed color (Y or y) and seed shape (R or r) in peas are on different chromosomes (4 individual chromosomes). During metaphase of meiosis I, different arrangements of the two chromosome pairs lead to different combinations of the alleles in the resulting haploid cells. On the left, the chromosome carrying the recessive y allele has segregated with the chromosome carrying the dominant R allele. On the right, the two chromosomes carrying the dominant alleles (Y and R) have segregated together. Note: For simplicity, this diagram shows only two pairs of homologous chromosomes, though eukaryotic cells typically have several different pairs of homologous chromosomes. [Extra Information] When meiosis begins, the DNA in each chromosome has already replicated, producing two sister chromatids. At metaphase I of meiosis, the two pairs of chromosomes randomly align themselves along the metaphase plate. This alignment can occur in two equally probable ways, shown on the two sides of the figure. On the left, the chromosome carrying the y allele is aligned on the same side of the metaphase plate as the chromosome carrying the R allele; Y is aligned with r. On the right, the opposite has occurred: Y is aligned with R, and y is with r. In each case, the chromosomes that aligned on the same side of the metaphase plate segregate into the same daughter cell. In this way, the random alignment of chromosome pairs during meiosis I leads to the independent assortment of alleles found on different chromosomes. For two genes found on different chromosomes, each with two variant alleles, meiosis produces four allele combinations in equal numbers (yR, Yr, YR, and yr), as seen at the bottom of the figure.If a YyRr (dihybrid) plant undergoes self-fertilization, any two gametes can combine randomly during fertilization. Because four kinds of gametes are made, 42, or 16, possible allele combinations are possible in the offspring. These genotypes, in turn, produce four phenotypes in a 9:3:3:1 ratio .This ratio is the expected outcome when a heterozygote for two genes on different chromosomes undergoes self-fertilization.

Answer 25

There are four possible ways that the chromosomes can align, and eight different types of gametes (ABC, abc, ABc, abC, Abc, aBC, AbC, aBc) can be produced.

Answer 26

For ethical and practical reasons.

Answer 27

Pedigree analysis The results of this method may be less definitive than the results of breeding experiments because the small size of human families may lead to large sampling errors. Nevertheless, a pedigree analysis often provides important clues concerning human inheritance.

Answer 28

The common allele and a rare allele that has arisen by mutation.

Answer 29

Whether the mutant allele is dominant or recessive and to predict the likelihood of an individual being affected.

Answer 30

1. Cystic fibrosis (CF) 2. 3% 3. Individuals who are homozygous for this allele exhibit the disease symptoms, which include abnormalities of the lungs, pancreas, intestine, and sweat glands. 4. Roman numerals. I denotes oldest while III would denote newest so on so forth. II would denote middle generation. 5. Males are squares, women are circles, horizontal lines directly connecting shapes are mates, vertical lines attached to horizontal lines denote offspring. If shapes are branched off the same horizontal line, they are siblings. Direct connections are only for mates. Filled shapes are affected, half-filled shapes are presumed heterozygous, and empty shapes are unaffected individuals

Answer 31

No. If two parents are affected with the disease, they would have to be homozygous for the mutant allele if it’s recessive. Two homozygous parents would produce all affected offspring, barring rare mutations. If they produce an unaffected offspring, then the mutant allele is not recessive.

Answer 32

The answer is that two unaffected individuals can produce an affected offspring. Such individuals are presumed to be heterozygotes (designated by a half-filled symbol). However, the same unaffected parents can also produce unaffected offspring (depicted by an unfilled symbol), because an individual must inherit two copies of the mutant allele to exhibit the disease. A recessive mode of inheritance is also indicated by the observation that all of the offspring of two affected individuals are affected themselves. However, for genetic diseases that limit survival or fertility, there are rarely if ever cases where two affected individuals produce offspring.

Answer 33

Huntington disease.

Answer 34

30 to 50 years old, and includes uncontrollable jerking movements of the limbs, trunk, and face; progressive loss of mental abilities; and the development of psychiatric problems.

Answer 35

All affected offspring having at least one affected parent suggests a dominant pattern of inheritance. However, affected parents do not always produce affected offspring. For example, II-6 is a heterozygote that has passed the nondisease-causing allele to his offspring, thereby producing unaffected offspring (III-3 and III-4).

Answer 36

On paired chromosomes called autosomes, these exclude the sex chromosomes. Huntington disease is an example of a trait with an autosomal dominant inheritance pattern, whereas cystic fibrosis displays an autosomal recessive pattern. However, some human genes are located on sex chromosomes, which are different in males and females. These genes have their own characteristic inheritance patterns

Answer 37

Sex chromosomes Sex chromosomes are found in many but not all species with two sexes.

Answer 38

The person is a female. In mammals, the presence of the Y chromosome causes maleness. Therefore, lacking a Y chromosome, a person with a single X chromosome develops into a female.

Answer 39

The SRY gene The X-Y System operates in mammals.

Answer 40

It operates in insects. THe Y chromosome does not determine maleness. Females in this system have a pair of sex chromosomes and are designated XX. In some insect species that follow the X-O system, the male has only one sex chromosome, the X. In other X-O insect species, such as Drosophila melanogaster, the male has both an X chromosome and a Y chromosome. In all cases, an insect’s sex is determined by the ratio between its X chromosomes and its sets of autosomes. If a fly has one X chromosome and is diploid for the autosomes (2n), this ratio is 1/2, or 0.5. This fly will become a male whether or not it receives a Y chromosome. On the other hand, if a diploid fly receives two X chromosomes, the ratio is 2/2, or 1.0, and the fly becomes a female.

Answer 41

Thus far, we have considered examples where females have two similar copies of a sex chromosome, the X. However, in other animal species, such as birds and some fish, the male carries two similar chromosomes. This is called the Z-W system to distinguish it from the X-Y system found in mammals. The male is ZZ, and the female is ZW.

Answer 42

Haplodiploid System. Females, queen and worker bees, are produced from fertilized eggs and are diploid. The Males, or drones, are produced from an unfertilized egg and are haploid. (one less gamete, the sperm)

Answer 43

Environmental Sex Determination Some reptiles and fish have their sex determined by temperature. For example, in the American alligator (Alligator mississippiensis), temperature controls sex development. When eggs of this alligator are incubated at 33°C, nearly all of them produce male individuals. When the eggs are incubated at a temperature significantly below 33°C, they produce nearly all females, whereas increasing percentages of females are produced above 34°C.

Answer 44

X is rather large carrying over 1,000 genes while the Y chromosome is quite small and carries less than 100 genes.

Answer 45

X-linked genes Y-linked genes. Much less common considering the size.

Answer 46

Sex-linked genes

Answer 47

The terms only apply to genes that are present in two copies. Males are XY hence no copy of the same gene in sex chromosomes for X-linked genes.

Answer 48

Hemizygous A male mammal is hemizygous for an X-linked gene.

Answer 49

False. X-linked refers to diseases more common in men.

Answer 50

Hemophilia. In individuals with hemophilia, blood does not clot properly, and a minor cut may bleed for a long time. Common accidental injuries that are minor in most people pose a threat of severe internal or external bleeding for hemophiliacs. Hemophilia A is caused by a recessive X-linked allele that encodes a defective form of a clotting protein. If a mother is a heterozygous carrier of hemophilia A, each of her children has a 50% chance of inheriting the recessive allele. The following Punnett square shows a cross between an unaffected father and a heterozygous mother. XH designates an X chromosome carrying the dominant functional allele, and Xh-A is the X chromosome that carries the recessive nonfunctional allele for hemophilia A. Although each child has a 50% chance of inheriting the hemophilia allele from the mother, only 1/2 of the sons will exhibit the disorder. Because a son inherits only one X chromosome, a son who inherits the recessive (disease-causing) allele from his mother will have hemophilia. However, a daughter inherits an X chromosome from both her mother and her father. In this example, a daughter who inherits the recessive allele from her mother also inherits a dominant allele from her father. This daughter will not have hemophilia, but if she passes the recessive allele to a son, he will have hemophilia.

Answer 51

Mendelian inheritance In the first section of this chapter, we considered the inheritance pattern of traits affected by a single gene that is found in two variants, one of which is dominant over the other. This pattern is called simple Mendelian inheritance, because the phenotype ratios in the offspring clearly demonstrate Mendel’s laws.

Answer 52

True. The transmission of these genes from parents to offspring does not usually produce the ratios of phenotypes we would expect on the basis of Mendel’s observations.

Answer 53

A wild-type allele. In most cases, a wild-type allele encodes a protein that is made in the proper amount and functions properly.

Answer 54

Mutant allele. These tend to be rare in natural populations. In the case of Mendel’s seven characters in pea plants, the recessive alleles are due to rare mutations.

Answer 55

These are called loss-of-function alleles. To understand why many loss-of-function alleles are recessive, we need to take a quantitative look at protein function.

Answer 56

The gene encodes an enzyme (protein P) that is needed to convert a colorless molecule into a purple pigment. The P allele is dominant because one P allele encodes enough of the functional protein—50% of the amount found in a PP homozygote—to provide a purple phenotype. Therefore, the PP homozygote and the Pp heterozygote both make enough of the purple pigment to yield purple flowers. The pp homozygote cannot make any of the functional protein required for pigment synthesis, so its flowers are white.

Answer 57

In other cases, however, an allele may be dominant because the heterozygote actually produces more than 50% of the functional protein. This increased production is due to the phenomenon of gene regulation. The dominant allele is up-regulated in the heterozygote to compensate for the lack of function of the recessive allele.

Answer 58

Pleiotropy Pleiotropy occurs for several reasons, including the following: The expression of a single gene can affect cell function in more than one way. For example, a defect in a microtubule protein may affect cell division and cell movement. A gene may be expressed in different cell types in a multicellular organism. A gene may be expressed at different stages of development.

Answer 59

In this genetics unit, we tend to discuss genes as they affect a single trait. This educational approach allows us to appreciate how genes function and how they are transmitted from parents to offspring. However, in all or nearly all cases, the expression of a gene is pleiotropic with regard to the characteristics of an organism. The expression of any given gene influences the expression of many other genes in the genome, and vice versa. Pleiotropy is revealed when researchers study the effects of gene mutations. As an example of a pleiotropic effect, let’s consider cystic fibrosis (CF), which we discussed earlier as an example of a recessive human disorderIn the late 1980s, the gene for CF was identified. The gene encodes a protein called the cystic fibrosis transmembrane regulator (CFTR), which regulates ion balance by allowing the transport of chloride ions (Cl–) across cell membranes. The mutation that causes CF diminishes the function of this Cl– transporter, affecting several parts of the body in different ways. Because the movement of Cl– affects water transport across membranes, the most severe symptom of CF is the production of thick mucus in the lungs, which occurs because of a water imbalance. Similarly, thick mucus can also block the tubes that carry digestive enzymes from the pancreas to the small intestine. Without these enzymes, certain nutrients are not properly absorbed into the body. As a result, persons with CF may show poor weight gain. Another effect is seen in the sweat glands. The Cl– transporter has the function of recycling salt out of the glands and back into the skin before it can be lost to the outside world. Persons with CF have excessively salty sweat due to their inability to recycle salt back into their skin cells. A common test for CF is the measurement of salt on the skin. Taken together, we can see that a defect in CFTR has multiple effects throughout the body.

Answer 60

Incomplete dominance

Answer 61

Carl Correns Shows a cross between two four-o’clock plants: a red-flowered homozygote and a white-flowered homozygote. The allele for red flower color is designated CR, and the white allele is CW. These alleles are designated with superscripts rather than upper- and lowercase letters because neither allele is dominant. The offspring of this cross have pink flowers—they are CRCW heterozygotes with an intermediate phenotype.

Answer 62

4 squares all labeled with alleles with subscripts since none of them are dominate. The cases where the resulting offspring have both red and white combinations would be pink. Same alleles in the other two offspring would be completely red or white.

Answer 63

Multiple alleles Particular phenotypes depend on which two alleles each individual inherits. ABO blood types in humans are an example of phenotypes produced by multiple alleles.

Answer 64

They are substances that may be recognized as foreign material when introduced into the body of an animal.

Answer 65

A and B antigens

Answer 66

By enzymes that are encoded by a gene that exists in three alleles, designated I^A, I^B, and i.

Answer 67

I^A and I^B.

Answer 68

They are ii homozygous and do not produce surface antigen A or B. The red blood cells of an IAIA homozygous or IAi heterozygous individual have surface antigen A (blood type A). Similarly, a homozygous IBIB or heterozygous IBi individual produces surface antigen B (blood type B). A person who is IAIB heterozygous makes both antigens, A and B, on every red blood cell (blood type AB). The phenomenon in which a single individual expresses two alleles is called codominance.

Answer 69

Codominance

Answer 70

Biochemists have analyzed the carbohydrate tree produced in people of differing blood types. The differences are shown schematically. In type O, the carbohydrate tree is smaller than in type A or type B because a sugar has not been attached to a specific site on the tree. People with blood type O have a loss-of-function mutation in the gene that encodes the enzyme that attaches a sugar at this site. This enzyme, called a glycosyl transferase, is inactive in type O individuals. In contrast, the type A and type B antigens have sugars attached to this site, but each of them has a different sugar. This difference occurs because the enzymes encoded by the IA allele and the IB allele have slightly different active sites. As a result, the enzyme encoded by the IA allele attaches a sugar called N-acetylgalactosamine to the carbohydrate tree, whereas the enzyme encoded by the IB allele attaches galactose. N-Acetylgalactosamine is represented by an orange hexagon in Table 17.2, and galactose by a green triangle.

Answer 71

Norm of reaction

Answer 72

No. You need a genetically homogenous population to study the norm of reaction. A wild population of squirrels is not genetically homogenous, so it could not be used.

Answer 73

The study of single genes. This focus allowed Mendel to formulate the basic laws of inheritance for traits with a simple dominant/recessive inheritance pattern. Likewise, this approach helped later researchers understand inheritance patterns involving incomplete dominance and codominance, as well as traits that are influenced by an individual’s sex.

Answer 74

Yes. For example, in both plants and animals, height is affected by genes that encode proteins involved in the production of growth hormones, cell division, the uptake of nutrients, metabolism, and many other functions. Variation in any of the genes involved in these processes is likely to influence an individual’s height.

Answer 75

The answer lies in the genotypes of his strains. Although many genes affect the height of pea plants, Mendel chose true-breeding strains that differed with regard to only one of those genes.

Answer 76

Gene interaction

Answer 77

An example is the unexpected gene interaction discovered by English geneticists William Bateson and Reginald Punnett in the early 1900s, when they were studying crosses involving the sweet pea, Lathyrus odoratus. A cross between a true-breeding purple-flowered plant and a true-breeding white-flowered plant produced an F1 generation with all purple-flowered plants and an F2 generation with a 3:1 ratio of purple- to white-flowered plants. Mendel’s laws predicted this result. The surprise came when the researchers crossed two different true-breeding varieties of white-flowered sweet peas. All of the F1 generation plants had purple flowers! When these plants were allowed to self-fertilize, the F2 generation had purple-flowered and white-flowered plants in a 9:7 ratio. From these results, Bateson and Punnett deduced that two different genes were involved. To have purple flowers, a plant must have one or two dominant alleles for each of these genes. The relationships among the alleles are as follows: C (one allele for purple) is dominant to c (white) P (an allele of a different gene for purple) is dominant to p (white) cc masks P, or pp masks C, resulting in white flowers in either case

Answer 78

Epistatic interactions often arise because two or more different proteins are involved in a single cellular function. For example, two or more proteins may be part of a metabolic pathway leading to the formation of a single product. This is the case for the formation of a purple pigment in the sweet pea strains we have been discussing: In this example, a colorless precursor molecule must be acted on by two different enzymes to produce the purple pigment. Gene C encodes a functional protein called enzyme C, which converts the colorless precursor into a colorless intermediate. The recessive c allele results in a lack of production of enzyme C in the cc homozygote. Gene P encodes the functional enzyme P, which converts the colorless intermediate into the purple pigment. Like the c allele, the p allele results in an inability to produce a functional enzyme. A plant homozygous for either of the recessive alleles does not make any functional enzyme C or enzyme P. When either of these enzymes is missing, the plant cannot make the purple pigment and has white flowers. Note that the results observed in Figure 17.19 do not conflict with Mendel’s laws of segregation or independent assortment. Mendel investigated the effects of only a single gene on a given character. The 9:7 ratio is due to a gene interaction in which two genes affect a single character.

Answer 79

Discrete trait. This was discussed in the examples of red and white eyes in fruit flies and round or wrinkled seeds in garden peas. These phenotypes do not overlap.

Answer 80

Quantitative traits. In humans, quantitative traits include height, weight, skin color, metabolic rate, and heart size. In the case of domestic animals and plant crops, many of the traits that people consider desirable are quantitative in nature, such as the number of eggs a chicken lays, the amount of milk a cow produces, and the number of apples on an apple tree. Consequently, much of our modern understanding of quantitative traits comes from agricultural research.

Answer 81

Polygenic For many polygenic traits, genes contribute to the phenotype in an additive way. Also, environmental factors often have a major effect on quantitative traits. For example, an animal’s diet affects its weight, and the amounts of rain and sunlight that fall on an apple tree affect how many apples it produces.

Answer 82

For many polygenic traits, genes contribute to the phenotype in an additive way. Also, environmental factors often have a major effect on quantitative traits. For example, an animal’s diet affects its weight, and the amounts of rain and sunlight that fall on an apple tree affect how many apples it produces.

Answer 83

Probability

Answer 84

The number of possible outcomes. For example, if you draw a card at random from a 52-card deck, the probability that you will get the jack of diamonds is 1 in 52, because 52 outcomes are possible. In contrast, only two outcomes are possible when you flip a coin, so the probability is one in two (1/2, or 0.5, or 50%) that the heads side will be showing when the coin lands.

Answer 85

P = number of times an event occurs divided by Total of number of possible outcomes

Answer 86

Because these events are independent of each other.

Answer 87

Random sampling error

Answer 88

Product rule. As we have already discussed, events are independent if the outcome of one event does not affect the outcome of another.

Answer 89

inheritance or heredity

Answer 90

pea, garden pea, peas, Pisum, or Pisum sativum

Answer 91

the variants of only one character

Answer 92

Blank 1: dominant | Blank 2: recessive

Answer 93

Genes; Alleles

Answer 94

quantitative experiments

Answer 95

3 axial: 1 terminal

Answer 96

single factor

Answer 97

two identical alleles

Answer 98

the variants of only one character

Answer 99

heterozygous

Answer 100

either homozygous dominant or heterozygous

Answer 101

male and female gametes

Answer 102

two identical alleles

Answer 103

Heterozygous

Answer 104

To determine the genotype of an individual with a dominant phenotype

Answer 105

Independent assortment

Answer 106

homozygous dominant heterozygous

Answer 107

Separation of homologous chromosomes during meiosis I

Answer 108

homozygous dominant

Answer 109

identical alleles different alleles new alleles

Answer 110

two different characters

Answer 111

Blank 1: homologous | Blank 2: pairs or pair

Answer 112

incomplete

Answer 113

norm, reaction

Answer 114

The yellow round was YYRR and the green wrinkled was yyrr

Answer 115

This skin tone is a recessive trait

Answer 116

The parents were carriers of the condition

Answer 117

Choose another drug as the individual will likely suffer from too much toxicity

Answer 118

There is a 25% chance that you will need to decrease the dosage of the drug WRONG

Answer 119

Increase the normal dosage because they are not making enough of the drug

Answer 120

9 yellow round: 3 yellow wrinkled: 3 green round 1: green wrinkled

Answer 121

The individual will have long eyelashes

Answer 122

Alleles for different traits do not have to be inherited together (ex. Red hair and blue eyes are not linked