Science 8 M7 & M8

Science 8 M7 & M8

Adaptations

Some species have specific adaptations, something that allows them to live in the habitat that they are currently in. Many have more than one. Some are well camouflaged like the polar bear, white in white. Others have tree climbing structures that allow them to make fast get aways from predators. Some have the ability to stay warm, extra layers of fat, or perhaps dense fur.

Multiple Choice

Penguins live in the Antarctic. Which of the following would be a good adaptation for the penguin?

• Black and White Colors

• Extra layer of fat for warmth

• Little wings

• Swimming under water

Non-native Species

If a species that is new to the area, perhaps hitched a ride in somehow, is destructive to the species currently living there, it is called an invasive species. There are many. More importantly, What do they do? If the species attacks a certain species in a tree, that species will decrease over time. If the invasive species attacks a ground species, the ground species will decrease over time as the attackers will destroy the ground species little by little.

Invasive Species

Sometimes these species are brought in for the right reasons but have ill gotten consequences.

Brown Tree Snake has devastated the economy in Guam and is fast spreading elsewhere.

They eat the food other species would eat. Harm crops harm human. Cane toad, Asian Mosquito, Burmese Python to name just a few.

Multiple Choice

Fire ants which are not native to Texas will aggressively attack bird's eggs that have a nest on the ground. Which is most likely to happen due to the fire ants arrival to Texas?

• Tree nesting bird population will decrease

• Tree nesting bird population will increase

• Ground nesting bird population will increase

• Ground nesting bird population will decrease

Reproduction

With asexual reproduction the outcome will be an exact duplicate, a clone. With sexual reproduction, the sex cells of both parents join to create a new cell creating genetic variation in the offspring. Budding is process of a new organism growing off of a parent organism. Binary Fission is asexual reproduction.

Multiple Choice

_____________reproduction happens when sex cells from both parents join.

• Binary Fission

• Asexual reproduction

• Sexual reproduction

• Budding

Inside the cell

Image on the left shows a cell with the nucleus and chromosomes inside. Middle image shows a chromosome highlighted from the nucleus. On the right is the DNA from the chromosome stretched out with a part of it selected on the right which is a gene.

Multiple Choice

What do you call a section of DNA that codes for a specific trait?

• Nucleus

• Gene

• Chromosome

• DNA

Gregor Mendel

Gregor Mendel is known as the Father of Genetics. During his research with pea plants, he never knew about genes, but he called them factors. He figured out dominant and recessive traits and what happened in various generations. He knew that even though the flowers of the plant might be all purple, in the next generation when he crossed them, he would get some white. The recessive would show up again. He knew that all that was needed was 1 dominant for the dominant trait to show but 2 recessives were required to be shown

Multiple Choice

A dominant trait shows up __________.

• only when two dominant alleles are present

• only when one dominant allele is present

• when at least one recessive allele is present

• when at least one dominant allele is present

Multiple Choice

A recessive trait only shows up when __________.

• two dominant alleles are present

• one dominant allele is present

• two recessive alleles are present

• at least one recessive allele is present

Punnett Squares

Punnett Squares deal with probability. What is the chance that something will happen. We work with 100% if the outcome is a for certain event. For instance. It is certain the offspring will have a certain color eyes. Therefore the probability they will be a color is certain. A square is divided into 4 each being 25% as that will be the only possible crosses. There are dihybrid which are crossing 2 traits but we will not cover that. Each parent has 2 alleles for the gene, that is the genotype. One parent on top, one parent on the side. The alleles get carried down and across. so that there is an allele from each parent in the 4 squares. Each square represent 25% of what might occur in the offspring.

Multiple Choice

Scientists use __________ to show what genotypes combinations or offspring traits are possible.

• Mendel Square

• Madison square

• Punnett square

• Times square

What do we have here?

We have 2 heterozygous parents, the alleles are different. We have 1 square, 25% probability of homozygous dominant brown eyes BB. we have 1 square, 25% bb, blue yes homozygous recessive and 50% probability of Bb . The genotypes are BB, Bb, and bb, The phenotypes are brown and blue eyes.

Can traits skip generations?

Yes! Sometimes in families all of sudden there is a baby with red hair and nobody has red hair! Upon further investigation, it turns out the some great great grandparents had red hair. That recessive gene can stay hidden for a long long time!

Natural selection

Over time, the stronger and best adapted to the environment survive. they pass on the traits that allowed them to live to their offspring and those offspring to their offspring while others that were not that well adapted did not survive as well. Eventually the species change over time or branched off into 2 species with different traits. Have you heard of the term "survival of the fittest"? Could that be another term for natural selection?

Mutations

Mutations is a change in the DNA in the gene which cause a change in the protein. Some are good, some bad, some do nothing. This is how species change over time. This is natural selection. It begins with a mutation that is helpful to the organism, it has offspring and so on. If the mutation or adaptation gives it a better chance to survive, so will its offspring.

Multiple Choice

Two organisms that are closely related would have

• very similar DNA

• exactly the dame DNA

• no proteins in common

• completely different DNA sequence