Land snails colonized a field fo yellow grass.  At first, the population contained two types of snails: brown and yellow banded snails.  After 10 years most of the snails had shells with yellow bands.  What process most likely led to an increase in the number of snails with yellow bands?

Land snails colonized a field fo yellow grass.  At first, the population contained two types of snails: brown and yellow banded snails.  After 10 years most of the snails had shells with yellow bands.  What process most likely led to an increase in the number of snails with yellow bands?

Natural Selection

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Why is the pesticide less effective each year in its ability to control the target population of insects.

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Why is the pesticide less effective each year in its ability to control the target population of insects.

The insects with greater resistances to the pesticide survived and passed down the trait to their offspring.

The idea that evolution takes place at one point in time, followed by a long period without change is called ____________.

The idea that evolution takes place at one point in time, followed by a long period without change is called

punctuated equilibrium.

The difference in the fur color of the individual rabbits is described as _______________ .

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The difference in the fur color of the individual rabbits is described as variation.

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A species of finch has been studied on one of the geographically isolated Galapagos Islands for many years.  Since the island is small, the lineage of every bird for several generations is known.  This allows a family tree of each bird to be developed.  Some family groups have survived and others have died out.  The groups that survived probably have ______________________.

A species of finch has been studied on one of the geographically isolated Galapagos Islands for many years.  Since the island is small, the lineage of every bird for several generations is known.  This allows a family tree of each bird to be developed.  Some family groups have survived and others have died out.  The groups that survived probably have inherited some advantageous variations.

In the early stages of development, the embryos of dogs, pigs, and humans resemble one another.  This observation suggests that thes animals may have __________________.

In the early stages of development, the embryos of dogs, pigs, and humans resemble one another.  This observation suggests that thes animals may have a common ancestry.

The long slow process of change in a species over time is __________________.

The long slow process of change in a species over time is

evolution.

The wings of a bird and the front legs of a dog are __________________.

The wings of a bird and the front legs of a dog are homologous structures.

Evolution can be defined as any changes in the relative frequency of alleles in the gene pool of a __________________.

Evolution can be defined as any changes in the relative frequency of alleles in the gene pool of a

population.

Modern sea star larvae resemble some primitive vertebrate larvae.  This similarity may suggest that primitive vertebrates __________________.

Modern sea star larvae resemble some primitive vertebrate larvae.  This similarity may suggest that primitive vertebrates share a common ancestor with sea stars.

Which principle describes genes that segregate without influence on each others inheritance?

Which principle describes genes that segregate without influence on each others inheritance?

independent assortment.

Eggs and sperm are ____________ formed by __________.

Eggs and sperm are gametes formed by meiosis.

The process of __________ reduces chromosome number from 2n to n.

The process of meiosis reduces chromosome number from 2n to n.

The law of segregation states that, during meiosis, each pair of alleles__________ .

The law of segregation states that, during meiosis, each pair of alleles separates .

To describe how traits can disappear and reappear in a certain pattern from generation to generation, Mendel proposed the law of __________ .

To describe how traits can disappear and reappear in a certain pattern from generation to generation, Mendel proposed the law of Independent Assortment .

Each body cell in an earthworm contains 36 chromosomes.  How many chromosomes are in each of its gametes?

Each body cell in an earthworm contains 36 chromosomes.  How many chromosomes are in each of its gametes?

Gametes contain 1/2 as many chromosomes so.... 18 chromosomes in the gametes.

Segregation of alleles occurs during __________ .

Segregation of alleles occurs during meiosis .

In a particular population, sexual reproduction can produce __________ .

In a particular population, sexual reproduction can produce many different phenotypes .

In a certain species of mouse, gray fur (G) is dominant over cream-colored fur (g).  If a homozygous gray mouse is crossed with a cream-colored mouse, the genotype of the F1 generation will most likely be __________ .

In a certain species of mouse, gray fur (G) is dominant over cream-colored fur (g).  If a homozygous gray mouse is crossed with a cream-colored mouse, the genotype of the F1 generation will most likely be 100% Gg .

GG x gg yields only Gg genotypes.

A cross between two plants that have pink flowers produced plants that have red, pink, or white flowers.  Which is the most likely explanation for these results?

A cross between two plants that have pink flowers produced plants that have red, pink, or white flowers.  Which is the most likely explanation for these results?

Incomplete dominance

The appearance of an organism is its _____________.

The appearance of an organism is its phenotype.

To determine the genotype of an individual that shows the dominant phenotype (DD or Dd), you would cross that individual with one that is ______________.

To determine the genotype of an individual that shows the dominant phenotype (DD or Dd), you would cross that individual with one that is homozygous recessive (dd)

to distinguish between DD or Dd.

A segment of DNA that controls a particular hereditary trait is called (an) ______________.

A segment of DNA that controls a particular hereditary trait is called (an) gene.

An organism having two different alleles for a trait is called ______________.

An organism having two different alleles for a trait is called a heterozygote.

An organism in which two alleles for a trait is different is  ______________.

An organism in which two alleles for a trait is different is  heterozygous.

In one plant, the allele for long stems (L) is dominant; the allele for short stems (l) is recessive.  A scientist crossed a heterozygous, long stemmed plant with a short stemmed plant.  Which of these shows the expected results of this cross?

In one plant, the allele for long stems (L) is dominant; the allele for short stems (l) is recessive.  A scientist crossed a heterozygous, long stemmed plant with a short stemmed plant.  Which of these shows the expected results of this cross?

Ll x ll yields 50% (Ll) long stemmed plant and 50% (ll) short stemmed plant.

A family has eight children.  Six children have second toes that are longer than the big toe.  Two children have second toes that are shorter than the big toe.  What are the most likely genotypes of the parents.

A family has eight children.  Six children have second toes that are longer than the big toe.  Two children have second toes that are shorter than the big toe.  What are the most likely genotypes of the parents?

The ratio in the children of 6/8 dominant and 2/8 recessive indicates a heterozygous cross. 

 Therefore, the parents had genotypes Tt and Tt.

In guinea pigs, black fur is dominant (B).  A black guinea pig is crossed with a white guinea pig.  If the litter contians a white offspring, the genotype of the black haired parent is probably ______________.

In guinea pigs, black fur is dominant (B).  A black guinea pig is crossed with a white guinea pig.  If the litter contians a white offspring, the genotype of the black haired parent is probably heterozygous.

Living things grow because _______.

Living things grow because they produce more and more cells through the process of mitosis.

Female gametes are called _______.

Female gametes are called eggs.

The cell that results from fertilization is called a _______.

The cell that results from fertilization is called a zygote.

Sex cells are also called  _______.

Sex cells are also called  gametes.