Reproduction As species reproduce, characteristics are passed from parents to offspring. - PowerPoint Presentation

Slide1

Reproduction

As species reproduce, characteristics are passed from parents to offspring.Slide2

Key Concepts

Asexual and sexual reproduction

InheritanceSlide3

Learning outcomes

Distinguish between asexual and sexual reproduction and describe examples of each type of reproduction.

Describe types of variations found within a species and determine whether they are discrete or continuous.

Distinguish between heritable and non-heritable characteristics.Slide4

Look around at the plants in our classroom

Imagine they are all alive (and that I am not currently in the process of killing the living ones).

What do you notice about them?Slide5

Different shapes, sizes,

colours

?

If there were 10 of each kind in the room, it might be easier to notice patterns and similarities among species.

Particular species have particular characteristics.Slide6

Boston Fern

Large green leaves and no real stem.Slide7

Coleus Plant

Leaves of many different

colours

growing out of a central stem.Slide8

Take a look in the classroom at your species

What characteristics do you see that are common to humans?Slide9

I wonder…

What process ensures that characteristics in a species are passed down from generation to generation?Slide10

ReproductionSlide11

Start Taking Notes Here!!

Through the process of reproduction, characteristics are passed on from one generation of a species to the next.

This may through asexual reproduction (one parent) or sexual reproduction (two parents).

Through sexual reproduction, the resulting cells contain different genetic information than the parent

cell(s

).

Asexual reproduction always results in the formation of cells with identical genetic information.Slide12

Therefore…

Sexual reproduction is a way of maintaining genetic diversity in a species or population.

Asexual reproduction allows for fast growth of a population of a population of identical individuals, which benefits species survival in a stable environment.

E.g. Slide13

Review: How

can Humans (or any species) be the same, but also different?

Individual members of a species can also have their own unique versions of certain characteristics… Remember eye

colour

, hair

colour

in humans… Or 2 plants of the same species can have dark purple leaves, while another’s is red and yellow.Slide14

Variation

In this section you will discover how these variations occur, and we’ll consider the ethical implications of whether or not artificially “selecting” for certain characteristics is a good idea for human beings to pursue.

“Designer” babies, animals, plants, food sources.Slide15

Build-A-Baby?Slide16

Variation

Review from last section… How does variation contribute to a species survival?Slide17

A genetically "healthy" population is defined as having a large amount of genetic variability.

With a large amount of genetic variation, natural selection is able to operate by altering the frequency of particular alleles (characteristics) in response to environmental conditions.

In dry conditions, plants that carry genes that are resistant to drought will survive.Slide18

Not all Variation is obvious

Can see hair/eye

colour

;

coloured

bands in the banded snail; different leaf

colours

.

But what can’t you see? Blood type; some trees (Jack Pines for example) exhibit resistance to drought better than others; some bacteria “super bugs” are resistant to antibiotics; resistance to disease in humans/plants/animals?

Why do some students get chicken pox and some never do? (not vaccines)Slide19

Scientists study…

Which characteristics are passed along from generation to generation.

How characteristics show up in individuals.

The role of the environment in variation.

Although ancient peoples did not know about modern-day genetics, they did understand that characteristics were passed from parents to offspring. A 6000 year old tablet has been found recording the characteristics of 5 generations of horses.Slide20

Observing variation in human characteristics

In our class… how many people have “double jointed” thumbs?

Have a thumb that is straight or points backwards (hitchhiker’s thumb)?

Have detached ear lobes?

Have a smooth or pointed hairline?Slide21

Dominant or Recessive?

A pointed hairline (widow’s peak) is a dominant trait.

Hitchhiker’s thumb is recessive.

Attached earlobes is recessive.

Therefore, we should expect about 75% of us to have the first trait, and only 25% of us to have the other two.Slide22

Heritable and Non-Heritable CharacteristicsSlide23

Heritable Characteristics

Are passed on from generation to generation

E.g. eye

colour

, hair type, skin

colour

.Slide24

Non-Heritable Characteristics

Are known as acquired characteristics; are not passed on to other generations.

Unfortunately, if your mom or dad learned to play the piano, or many languages, or how to sew… you were not born knowing how to do those things.

The ability to play an instrument is an acquired characteristic, as is dyed hair. If you

colour

your hair red, green, blue, purple, yellow, tan, tangerine, orange, brown, black, white, or striped… your children will not inherit the dyed

colour

.Slide25

Inherited Predisposition

Do not confuse the inherited predisposition of musicality, with the ability to play an instrument.

While someone might inherit a musical ability, would they automatically know how to play an instrument they were handed after being raised in a culture where music wasn’t played/after never hearing music?Slide26

Discrete and Continuous VariationSlide27

Discrete Variation

The term refers to characteristics that have a defined form.

“either/or” variation

You either have blue eyes, or you do not have blue eyes; you either have blond hair or you do not have blond hair.

Your earlobes are either attached, or they are not.Slide28

Continuous Variation

Term refers to differences in characteristics that have a range of forms.

Consider height… adult humans come in a range of many different heights; there are many possible variations in height.

Weight (mass) is also a variation that is continuous (although wouldn’t it be great if I could inherit skinny?).

Shortest? Tallest?Slide29
Slide30
Slide31

Variation and the Environment

Some variations in individual organisms result from interactions with the environment. Slide32

If you take 2 plants of the same species and plant one in a sunny window, and the other in a dark closet, the two plants would soon begin to look very different.

Remember our class discussion about how humans have grown taller over time? This was a combination of a heritable characteristic and environmental interaction. Slide33

For example, North Americans are generally taller than they were in the 19

th

century because of better nutrition and access to a wide variety of food.

Variations caused by interactions with the environment are not heritable. An offspring of that plant grown in the closet would not look like its parent unless it was grown in the same conditions.

If a child of tall parents doesn’t receive proper nutrition, he or she will probably not be as tall as his or her parents.Slide34

Is it discrete or continuous?

Activity: Close your eyes and quickly grasp your hands together above your head, interlocking your fingers. Now look to see which thumb is one top, right or left?

Which way feels more natural?

From class data, is there a hand-clasping preference?

Is this an example of a discrete or continuous trait?Slide35

Check & Reflect

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