Download Key Concepts - O. Henry Science

Grade-Level Science Homework
Due: Friday, October 12, 2012
Name: ______________________________
Teacher: ____________
Period: ____
Key Concepts:
Key Concept 1: Heredity is the process by which characteristics are passed from parents to their
offspring. The units of inheritance are genes and are stored within the chromosomes in the nucleus
of a cell.
Key Concept 2: Genetic information is inherited from both parents in sexual reproduction. Inherited
traits include expressed external characteristics such as eye color and hair color and internal
characteristics such as blood type. Inherited traits are not affected by the organism’s surroundings.
Key Concept 3: Alleles are possible variations of a gene. Alleles occur in pairs, and individuals inherit
one allele from each parent. The combination of inherited alleles is the genotype of an individual.
Traits that are visibly apparent are an individual’s phenotype.
Key Concept 4: Both alleles are not always expressed in the offspring’s phenotype. Some alleles are
dominant (always expressed) and recessive (only expressed in the absence of a dominant allele.)
Part II: Defend Yourselves!
Image a couple of aliens travel to Earth to complete a
descriptive investigation of humans. They observe many
different humans, and conclude that all humans look alike. In
fact, they find humans so boring and ugly that they decide to
destroy us all. You are offended by their conclusion and
angered by their decision. In response, you decide to argue
that they are wrong, and claim that humans are not all alike.
Use the vocabulary words in the box to compose an argument
against the alien’s conclusions.
Vocabulary:
□ DNA
□ Trait (s)
□ Gene(s)
□ Nucleus
□ Cell(s)
□ Variation
□ Parent’s
Dear Kang and Kodos,
I am offended that you think humans are ugly and all look the same. In fact,
__________________ show lots of variation (variation is human word that means
“differences”). For example, some humans have blue eyes while other humans have
green, brown, or grey eyes. And, some humans are tall, while others are short. Each
trait is controlled by at least one __________________ I’m not sure about you, but all of our
genes are coded in our __________________ which stores all of our genetic information. It is
impossible for us to look exactly like our __________________ because our DNA is mixture of
their DNA. Also, our DNA can change because of mutation. When a mutation happens,
a base is changed in our DNA, which can change the function of a gene and create a
whole new trait. Mutations increase the __________________ in a population of organisms.
True, all humans are eukaryotic organisms, and we safely keep our DNA inside the
__________________ of our __________________ but we are definitively not all alike. Finally, you
are the ugly ones; not us! Please don’t destroy us 
Sincerely,
A concerned student of earth