Heredity and Traits

Once students understand how organisms have a life cycle, they focus on one step in all life cycles: reproduction. In this lesson, they analyze how traits are passed from parents to offspring, and how there are similarities but also variations in inherited traits.

• All organisms have traits, which are physical or behavioral characteristics of an organism.
• Traits are passed down from parents to offspring, which is heredity.
• Adaptations are traits that help an organism survive in its environment. Sometimes a variation in traits gives certain individual organisms a survival advantage, making it easier for them to get food or water or avoid predation.
• Some traits are influenced by the environment.
  
  

• How do organisms get their traits?
• How is the inheritance of traits connected to an organism’s life cycle?
• What causes parents and their children to resemble each other?
• Why, given that offspring inherit traits, aren’t all organisms exactly the same as their parents?
• How does the bee trait of color help the bee survive?
• How does the variation of traits lead to adaptations over time?
• How is size an example of an inherited trait that is also influenced by the environment?
• How would a lack of water likely affect the height of a normally tall plant?
  
  

Misconception: Living things can come from nonliving sources (i.e., seeds, eggs, and pupae are nonliving).

Fact: Living things come from living things. Seeds, eggs, and pupae are all living things, just different stages of life.

Misconception: All organisms have the same life cycle.

Fact: Organisms can have different life cycles, but they all go through birth, growth, reproduction, and death

Adaptation : a trait that helps an organism survive in its environment

Change : to make something different from what it is now

Function : the normal action of something or how something works

Heredity : the passing on of traits from parents to children

Inherit : to receive a trait from your parents or ancestors

Life Cycle : the series of developmental stages an organism passes through on its way from birth to death

Metamorphosis : a life cycle with a change from an immature form to an adult form

Reproduction : the ability of a mature organism to have offspring

Structure : the way in which parts are put together to form a whole

Trait : a physical or behavioral characteristic of an organism

Heredity

The exoskeleton is an example of a trait. A trait is a physical or behavioral characteristic of an organism. The honeybee stomach is another trait.

Parents pass along traits to their offspring when they reproduce. This passing on of traits from parents to children is called heredity. Heredity causes offspring to have traits that are similar to their parents and to their siblings.

Beekeepers are very interested in heredity. There are patterns that occur as traits get passed along. For example, some groups of honeybees are better able to survive through the winter. Other groups produce large amounts of honey. These traits get passed along in the bee’s life cycle from the queen to the eggs that she lays.

Variation of Traits

Heredity explains why offspring look similar to their parents. All of the honeybees in a beehive have a similar color. They are light brown in color and have light and dark stripes on their bodies. This is because they inherited that trait from their parents. To inherit means to receive Color is a physical trait. a trait from parents or ancestors.

Heredity explains why baby giraffes have long necks, just like their parents. A long neck is an inherited trait. Heredity also explains why worker bees gather nectar and pollen from flowers. This is a behavioral trait. Another behavioral trait is baby giraffes eating leaves from tall trees. However, offspring don’t look or act exactly like their parents. There are always some differences. These differences are called variations. For example, one baby giraffe might have a neck that is a little shorter than its parents or siblings. A worker bee might have wings that are a little shorter or longer than another worker bee.

In this lesson, students investigate how traits are passed down from parents to offspring and also develop a question that will allow them to test how the color variation of a moth might affect its survival in its environment. For the first part of the investigation, students graph and analyze data on the height of two different groups of tomato plants: those in the shade and those in the sun. In Part 2, students collaboratively conduct an investigation that tests how moths with different color patterns survive over time in a forest environment with predatory birds. They calculate how many moths survive predation in each trial, and the average number of moths eaten for each trial. Students use the data they gathered in both parts to construct an explanation for how traits are passed down from parents to offspring, and how this scientific phenomenon helps to explain variation in traits among individual organisms.