If two parents play piano beautifully, will their children be born knowing how to play? No. Playing the piano is learned, it is not a heritable trait.
Inheritance Transmission of characteristics from parents to offspring The characteristics of the parents are carried to the next generation by the process of heredity
What are Non-Heritable Traits? Characteristics are acquired and not necessarily passed on from generation to generation. Athleticism, artistic ability, leadership qualities are all learned during the early years of life.
A Closer Look at Variation
We’ve seen how variation is contributes to the survival of a species We’ve seen how variation is contributes to the survival of a species. Now let’s take a closer look at the different types of variation. Variations can either be discrete or continuous.
Discrete Variations Discrete variations are differences in characteristics that have a definite form. One characteristic, or the single, other variation, of the characteristic. Either the organism has a trait or it does not. Example: Either your earlobes are attached or they are not.
Discretely varying traits are traits that can be put into categories, like eye color.
Continuous Variation Variations are differences in characteristics that have a multitude of variations, such as height, shoe size, arm length etc…
Continuously varying traits cannot easily be put into categories since they vary along a range. Height (in humans or plants, etc.) is an example.
Variation and the Environment Some variations may be influenced by interactions with the environment. These variations are not inherited. Examples include: Change in the pigmentation of skin color throughout the seasons due to the sun. Height and weight can be influenced by diet.
Discretely varying traits are traits that can be put into categories, like eye color.
Continuously varying traits cannot easily be put into categories since they vary along a range. Height (in humans or plants, etc.) is an example.
Is it Discrete or Continuous? Page 29 Action Right Preference Left Preference Type (circle one) Clasping Hands Continuous Discrete Folding Arms
Let’s practice!
Blood type
Cranial volume
eye colour
Skin pigmentation
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Sample Multiple Choice Questions Q1. To better understand variation; scientists explore the characteristics, which are passed on from generation to generation within a species. Those characteristics that are passed on from generation to generation are … A. genetic B. inherited C. non-inherited D. non-genetic
Sample Multiple Choice Questions Q2. An albino kangaroo is a kangaroo that is pure white. This characteristic is classified as a … A. non-inherited variation B. continuous variation C. discrete variation D. singular variation
Sample Multiple Choice Questions Q3. Variations caused by interactions with the environment are not heritable. Plants that are grown in dim lighting conditions would turn out to be … A. identical to their parents in all aspects B. much like their parents C. very different from their parents D. similar to parent plants that were grown in dim light
Sample Multiple Choice Questions Q4. Cats B and C are similar in size, but cat A is taller when standing. Like humans, cats pass down genetic information for height, but cats can mature to be a wide range of heights - it is not an "either/or" characteristic. The characteristic of height in cats can be described as a non-heritable and continuous in variation heritable and discrete in variation heritable and continuous in variation non-heritable and discrete in variation
Answers to Previous Questions B C D
Did you … … identify the role of variation in species survival under changing environmental conditions? … describe examples of variation of characteristics within a species, and identify examples of both discrete and continuous variation? … distinguish those characteristics that are heritable from those that are not heritable, and identify characteristics for which heredity and environment may both play a role?