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8th science > Science Semester Two Final > Flashcards

Science Semester Two Final Flashcards

1
Q

What is DNA?

A

The molecule that carries genetic information for the development and functioning of the organism

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2
Q

What is the structure of DNA?

A

Double helix composed of code written in four chemical bases. DNA is organized into structures called chromosomes. An individual has paired sets of chromosomes (humans have 23). A gene is a segment of DNA located on the chromosomes of cells. The different gene forms are called alleles. Each allele governs a characteristic.

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3
Q

What does DNA determine in organisms?

A

DNA determines all your traits.

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4
Q

What is RNA vs DNA?

A

DNA is a double-stranded molecule that has a long chain of nucleotides. RNA is a single-stranded molecule which has a shorter chain of nucleotides.

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5
Q

What is mRNA? What is mRNA used for?

A

DNA is transcribed (copied) to mRNA. mRNA is translated (make readable) to protein.

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6
Q

What is a nucleotide? Name the four nucleotides.

A

A nucleotide is a chemical base of DNA. The four nucleotides are adenine (A), guanine (G), cytosine (C), and thymine (T). These chemicals bond in specific base pairs of AT and CG combinations supported by sugar phosphate structures that act as support.

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7
Q

What is a codon?

A

A trinucleotide (three letter) sequence of DNA or RNA that corresponds to a specific amino acid.

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8
Q

What do codons determine in organisms?

A

Codons correspond to amino acids. These amino acids serve as the building blocks for proteins.

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9
Q

Summarize protein synthesis.

A

Protein synthesis is the creation of proteins by the cells for a function. It consists of two processes - transcription and translation. During transcription, DNA is used as a template to make a molecule of messenger RNA (mRNA). During translation, the genetic code in mRNA is read and used to make a protein.

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10
Q

How are codons related to protein synthesis?

A

DNA is read in codons. Each codon instructs the cell to add a single amino acid to the protein chain.

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11
Q

What are traits?

A

Genetically determined characteristics

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12
Q

What are genes?

A

A segment of DNA located on the chromosomes of cells.

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13
Q

What are amino acids?

A

The fundamental molecules that serves as the building block for proteins

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14
Q

What are proteins?

A

Large, complex molecules that are required for the structure, function, and regulation of the body’s tissues and organs. Made up of long, folded amino acids. Critical to most of the work done by cells.

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15
Q

What is the relationship between traits, genes, and proteins?

A

The cell builds proteins using instructions found in genes. Specifically, the order of nucleotides in a gene determines the order of amino acids in one or more proteins. These proteins have functions that affect the organism’s traits.

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16
Q

Why are there 64 codons, but only 20 amino acids?

A

There are 64 possible codons because DNA is made up of four bases, and each codon is made up of three bases. The four bases are A, C, U, and G, and they can be combined in 64 different ways. However, there are only 20 possible amino acids, so some codons can code for multiple amino acids.

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17
Q

What is a chromosome? What are chromosomes made of?

A

Chromosomes are the structures that DNA is organized into. An individual has paired sets of chromosomes (Humans have 23 chromosomes.) Chromosomes are made of DNA and proteins.

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18
Q

What are mutations? When can they happen? Which types are passed down? What are the four types?

A

Mutations are changes in the DNA sequence of an organism. DNA errors can occur during cell division, exposure to mutagens, and/or viral infection. Germline mutations )sperm and egg cells) can be passed down. Somatic mutations (body cells) are not passed down. The mutation types are deletion, insertion, substitution, and frameshifts.

19
Q

Do mutations always have a negative impact? Explain.

A

No, sometimes mutations can have no change or positive change depending on their context and location.

20
Q

What is a Punnett Square? What are they used for?

A

Punnett squares are used to predict the genotype chances of offspring as well as their phenotypes.

21
Q

What is homozygous?

A

Homozygous dominant in the same (both uppercase) dominant alleles. Ex. GG. Homozygous recessive is the same (both lowercase) recessive alleles. Ex. gg.

22
Q

What is heterozygous?

A

Two different alleles (one uppercase, one lowercase). Ex. Gg

23
Q

What is “recessive?”

A

Recessive traits “hide” in our trait expressions (“lose”)

24
Q

What is “dominant?”

A

Dominant traits “win” in our trait expressions (“show”)

25
Q

What is a genotype? What is a phenotype?

A

A genotype is the combination of alleles that an organism receives from its parents. A phenotype is the observable traits of an organism (physical appearance). Genotypes are often represented by letter symbols, with dominant alleles being shown with capital letters and recessive alleles being shown with lowercase letters. While the genotype may be Bb, the phenotype is B.

26
Q

What is natural selection? What causes natural selection?

A

Natural selection is a process by which a population’s environment determines which traits are beneficial and which are not.

27
Q

What is selection pressure? Name two examples of selection pressure.

A

A selective pressure is an evolutionary force that causes a particular phenotype to be more favorable. The selective pressure is typically an environmental factor but can also be humans in artificial selection.

28
Q

What is genetic variation?

A

Genetic variation refers to the difference between organisms in a population. This variation can be differences in physical features, behaviors, or any other characteristics that are measurable.

29
Q

What is artificial selection? Name an example.

A

The human control of reproduction in order to influence the traits present in offspring. Humans breed dogs to have the traits they want.

30
Q

What is the difference between natural and artificial selection?

A

Natural selection is any selective process that occurs due to the fitness of an organism to its environment. Artificial selection is the selective breeding, typically imposed by humans, in order to increase the frequency of desired traits.

31
Q

What is selective breeding? How is selective breeding an example of artificial selection?

A

Selective breeding is a type of artificial selection in which plants and animals are bred to produce offspring with specific traits.

32
Q

What is genetic modification? Name an example of genetic modification/engineering.

A

Genetic modification is the process of modifying DNA for practical purposes. Genes can be inserted to produce desirable traits. This must be done to cells passed to offspring.

33
Q

What is the difference between microevolution and macroevolution?

A

Microevolution refers to small changes over short periods of time within a population. Macroevolution refers to larger changes over a long time scale

34
Q

Does natural selection take a short or long amount of time to select for genes? Explain.

A

Natural selection takes a long time to select for genes, as it slowly evolves the creatures to match their environments.

35
Q

What are the different ways a new species can emerge?

A
  1. Behavioral Isolation: occurs when two populations are capable of interbreedings but have differences in courtship rituals or other reproductive strategies that involve behaviors. 2. Geographical Isolation: occurs when two populations are separated by geographic barriers such as rivers or mountains. 3. Temporal Isolation: occurs when species reproduce at different times. 4. Reproductive Isolation: occurs when two populations cannot interbreed and produce fertile offspring. 5. Ecological Isolation: occurs when species live in the same region but occupy different habitats.
36
Q

What is an invasive species?

A

A species of plant or animal that outcompetes other species, causing damage to an ecosystem

37
Q

What is the difference between a native and invasive species?

A

Native: a species that originated and developed in its surrounding habitat and has adapted to living in that particular environment. Invasive: a species of plant or animal that outcompetes other species, causing damage to an ecosystem.

38
Q

How does the introduction of an invasive species impact the native ecosystem?

A

Invasive species can affect an ecosystem in many different ways. Each and every ecosystem is immensely complicated, and any change can have drastic consequences. Invasive species can take over an ecosystem and other populations’ resources.

39
Q

How is competition related to the interaction between two species?

A

Individuals with a population often compete with each other for resources. Populations in a community also compete for resources.

40
Q

What are renewable resources? Name two examples of renewable resources.

A

Renewable energy are sources that naturally renew or replenish themselves. These are things such as solar energy, wind energy, geothermal energy, biomass energy, and hydroelectric energy. Geothermal energy is energy from Earth’s heat. Biomass energy is any energy from material that comes from plants, animals, and microorganisms that were recently living. Hydroelectric energy is made by flowing water.

41
Q

What are non-renewable resources? Name two examples of non-renewable resources.

A

Nonrenewable energy is energy that comes from sources that will run out of energy and will not be replenished in our lifetime or even in many, many lifetimes. Most nonrenewable energy sources are fossil fuels, such as coal, petroleum (oil), and natural gas. Fossil fuels originated from plants and animals that existed millions of years ago. They were formed by high heat and pressure underground.

42
Q

What are limited resources? Name two examples of limited resources.

A

Limited resources are resources that are in finite qualities and can be depleted. Oil, coal, natural gasses.

43
Q

What are unlimited resources? Name two examples of unlimited resources.

A

Unlimited resources are resources that are available in unlimited quantities. Air, light, wind.

8th science (4 decks)

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