How can the environment affect phenotypes?
You may have noticed that the same plant
species grows better in a shady part of a yard than in a sunny part. The data in the table below
describe the growth of 50 seeds over a period of 10 days. The seeds were planted in two
different areas and began to emerge from the soil on day 4.
1. On graph paper, graph the average plant height for each area. Use different colored markers
for each area and include a key.
2. Make a similar graph of the average number of leaves for each area over the 10 days.
Analyze and Conclude
1. Infer Based on the data, what inference can you make about the two areas?
The environmental conditions were probably different in the two locations because the plants
grew differently.
2. Key Concept What environmental factors might have caused the differences in the
phenotypes?
Students might suggest sunlight, nutrients in the soil, or how close the seeds were planted
together. Some students might suggest that insects or small animals could have eaten the
leaves off the plants in Location 1.
Directions: Complete the crossword puzzle with the correct terms from the word bank.
gene genotype inheritance
mutation phenotype trait
Across Down
1. a distinguishing characteristic of 2. the passing of traits from generation
an organism to generation
5. a section of DNA that has genetic 3. an organism’s complete set of genes
information for one trait
4. how a trait appears or how it is
6. a permanent change in the expressed
sequence of DNA in a gene
Across 1. trait; 5. gene; 6. Mutation
Down 2. inheritance; 3. genotype; 4. phenotype
Practice
1. A mosquito has 6 chromosomes. How many different chromosome combinations can form in
the offspring?
8
2. Corn has 20 chromosomes. How many different chromosome combinations can form in the
offspring?
1,024
3. A human has 46 chromosomes. How many different chromosome combinations can form in
the offspring?
8,388,608
4. A capuchin monkey has 54 chromosomes. How many different chromosome combinations
can form in the offspring?
134,217,728
Directions: Use your textbook to respond to each statement.
1. Offspring resemble their parents because the traits of parents are inherited. List some of the
traits you have inherited from your parents. For each trait, choose the parent who the trait likely
came from. Then describe a trait that did not come from your parents.
Possible answers: Inherited traits could include eye color, hair color, general height, facial
features, and other physical characteristics. Non-inherited traits could include learned behaviors
and abilities. Students should assign the inherited traits to the appropriate parent.
2. Genes are the means of passing on traits. Define a gene in terms of the following: DNA,
chromosome, and genetic information.
a. Genes are made up of segments of DNA;
b. Chromosomes are made up of many genes;
c. Genes are codes for genetic information that is passed on to offspring.
3. The environment often influences traits. Recall environmental factors that can influence the
expression of phenotype.
Possible answers: Environmental factors such as diet, light, temperature, moisture, and
population density in a community can cause differences in the way a phenotype is expressed.
4. A mutation is a permanent change in the sequence of DNA in a gene. Explain why some
mutations are passed on to offspring and others are not.
A mutation in the genes of sperm and egg cells is inherited by offspring. Other gene mutations
are not passed from parents to offspring.
Directions: Label this diagram by writing the correct term from the word bank on each line.
cell nucleus chromosome DNA strands gene
DNA strands
cell nucleus
gene
chromosome
Directions: Answer each question or respond to each statement on the lines provided.
5. How are genes related to DNA?
Genes are distinct segments of DNA.
6. What is the role of genes in inheritance?
Each gene carries genetic information for one trait.
7. Describe the two ways in which organisms pass inherited traits to their offspring
Organisms pass inherited traits to their offspring through asexual or sexual reproduction. During
asexual reproduction, organisms produce offspring that are identical to themselves by cell
division and mitosis. During sexual reproduction, organisms produce offspring that are similar
but not identical to the parents.
Directions: On each line, write the term from the word bank that correctly completes each
sentence. Some terms will be used more than once. environment genotype nutrients phenotype
physical factors social factors social group social phase solitary phase
1. An organism’s complete set of genes is its genotype.
2. The phenotype of a trait is how the trait appears or how it is expressed.
3. A(n) genotype is unchanged throughout an organism’s life.
4. A(n) phenotype can change throughout an organism’s life.
5. Phenotypes result from the interactions of an organism’s genes and its environment.
6. Light, temperature, and moisture are physical factors that can influence an organism’s
phenotype.
7. Flamingos are born white, but they turn pink because of the food they eat; this is an example
of how nutrients, a physical factor, can affect phenotypes.
8. Social factors can also affect an organism’s color, body structure, or behavior.
9. The size of a desert locust’s social group can affect its phenotype.
10. The desert locust is green in its solitary phase.
11. The desert locust is yellowish-brown in its social phase.
(PAGE 20)
Directions: On the line before each statement, write T if the statement is true or F if the
statement is false. If the statement is false, change the underlined word(s) to make it true. Write
your changes on the lines provided.
F; phenotype, cannot 1. When an organism’s genotype changes in response to its environment, the organism’s genes are
not affected and the change can be passed on to the next generation.
F; a permanent 2. A mutation is a temporary change in the sequence of DNA in a gene.
T 3. A mutation is the only way that a trait can change so it can be passed to the next generation.
T 4. Only mutated genes in egg or sperm cells are inherited.
F; Most 5. Few mutations occur randomly.
T 6. Mutations can affect an organism’s ability to survive in its environment.
F; sometimes 7. Mutations are always harmful to an organism.
T 8. Mutations can spread to an entire population.
Directions: Answer each question or respond to each statement.
1. Analyze How does reduced genetic variability result in a weaker population?
When a population becomes genetically similar, there are fewer characteristics that would help
a species survive if the environment changes. If a disease is introduced to a genetically similar
population, fewer individuals would have a variant gene that would help them survive. All the
individuals of a population would be vulnerable. It is genetic variability that forms the basis for
natural selection and evolution of a species.
2. Summarize Describe one advantage and one disadvantage of parthenogenesis adaptation in
a large vertebrate, such as a Komodo dragon.
Possible answer: One advantage is that a lone female could still reproduce and replace a
population if all the males were lost. A disadvantage is the lack of genetic variability in a
parthenogenic population. Komodo dragons produce males by parthenogenesis, so sexual
reproduction could resume.
