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Biology Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Reproductive organs in mammals

A

Testes and ovaries

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2
Q

Process of fertilisation

A
  1. Sperm and egg united in fallopian tubes
  2. They form a zygote
  3. Zygote reaches the uterus and becomes a blastocyst
  4. The blastocyst burrows into the lining of the uterus and is implanted
  5. Inner cells of blastocyst become the embryo
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3
Q

Define chromosomes

A

Thread-like structures found in the nuclei of cells that carries genetic information in the form of genes

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4
Q

Importance of chromosomes to inheritance

A

Each person has 23 chromosomes from both their father and mother, making 46. This means that your features are a mix of both father and mother. People who don’t have 46 usually have syndromes which can affect their height and intellect

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5
Q

Significance of karyotypes

A

A karyotype is a person’s complete set of chromosomes. Presence of the Y chromosome indicates sex. Abnormal karyotypes can reveal disorders

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6
Q

Compare mitosis and meiosis

A

Mitosis is done everywhere outside the reproductive organs. The nucleus is split in two and the parent cell splits into two daughter cells. Full genetic information is passed onto them.

Meiosis is done only in the reproductive organs. The cell is split into four daughter cells and half the information is carried on.

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7
Q

Explain how genes are passed from parents to offspring in the gametes

A

A gamete (reproductive cell) contains one set of 23 chromosomes. When male and female gametes fertilise, the embryo has 2 sets of 23 chromosomes, fusing the parents’ characteristics.

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8
Q

Referring to gene inheritance, explain the similarities between parents and offspring

A

Parents and offspring are similar due to how inheritance works. The embryo contains one set of 23 chromosomes from both parents so they will share traits

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9
Q

Define a gene

A

A length of DNA that codes for a specific characteristic

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10
Q

Outline the key components of DNA

A

Double helix strand, sugar phosphate backbone, hydrogen bonding between bases of adenine, thymine, guanine and cytosine. Information is passed from DNA to RNA to proteins.

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11
Q

Outline the Strawberry DNA experiment

A
  1. Crush a strawberry in a plastic bag
  2. Create a dish soap water solution
  3. Add in crushed strawberries
  4. Add in salt
  5. Mix well
  6. Pour through gauze to remove solids
  7. Add the same amount of isopropyl alcohol as there is strawberry solution
  8. Observe white strands of DNA become isolated on top
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12
Q

Distinguish between DNA, genes and chromosomes

A

A chromosome is the DNA packaged into an X or Y shaped structure located in the nucleus of a cell. A gene is a segment of DNA. DNA is a double-helix strand containing a sugar-phosphate backbone and has bases of adenine, thymine, guanine and cytosine.

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13
Q

Explain how DNA is replicated.

A
  1. The double helix is opened by an initiator protein
  2. Helicase breaks the hydrogen bonds between the ATGC bases
  3. Primase briefly attaches to each base and assembles a foundation for replication
  4. DNA polymerase wraps itself around the bases
  5. Attaches new nucleotides in two ways: leading strand is continually attached, and the lagging strand is attached in discontinuous bursts
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14
Q

Outline the nature of the genetic code and base triplet hypothesis

A

Genetic code refers to the sequence of codons (or bases) in DNA or RNA. 3 bases form a codon. Each codon stands for 1 amino acid. There is a start codon (TAC) and stop codon (ATT, ATC or ACT). Most codons represent a specific amino acid

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15
Q

Steps involved in protein synthesis

A
  1. A gene’s DNA sequence is transcribed to make an RNA molecule.
  2. Transcription begins when RNA polymerase binds to a promoter sequence then uses DNA strands to make a new, complementary RNA molecule
  3. Transcription ends in a process called termination.
  4. Process is initiated when a ribosome combines with mRNA
  5. Amino acids are brought to the ribosomes to elongate the chain
  6. Polypeptide is released
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16
Q

Define mutation and mutagen

A

Mutation: Any change in the nucleotide sequence (ATGC)
Mutagen: Something which causes the DNA to permanently change (e.g. UV exposire)

17
Q

Describe how mutations change phenotypes

A

Mutations can generate new alleles which can change a person’s appearance and hence phenotype

18
Q

Are mutations harmful?

A

Most are harmful, some are neutral and a few are beneficial

19
Q

How is mutation important to natural selection and variance?

A

Mutation can create new alleles, which introduces new alleles to a population. New adaptive features can be created and this means some animals may have an advantage, allowing them to survive

20
Q

Outline Mendel’s work

A

Mendel ran an experiment selectively breeding peas. His work established traits are passed from parents to offpsring.

21
Q

Define the following: allele, homozygous, heterozygous, recessive, dominant, homologous, phenotype, genotype

A

Allele: The letters denoting a genotype
Homozygous: Identical alleles (BB)
Heterozygous: Different alleles (Bb)
Recessive: Allele that can be masked by a dominant
Dominant: Allele that masks a recessive
Homologous: Similar features internally or in a chromosome (e.g. same bone in different animals)
Phenotype: Physical appearance resulting from a gene combination
Genotype: 2 alleles resulting in genetic makeup

22
Q

Compare dominant-recessive inheritance patterns with those traits showing co-dominance, partial dominance and sex linkage

A

Dominant-recessive inheritance: Usually looks like Bb, where one allele is masked by another
Co-dominance: Both traits are expressed equally
Partial dominance: Trait is expressed to an extent
Sex linkage: Some diseases (e.g. hemophilia) can only be carried in the sex chromosomes

23
Q

Dominant and recessive genetic diseases

A

Dominant: Huntington’s disease (Breakdown of brain function), Marfan syndrome (affects connective tissues and alters the normal body length ratio - short torso, long digits and long limbs)
Recessive: Sickle-cell anemia, cystic fibrosis (damages lungs and digestive tract)

24
Q

How fossils are used to suggest age of earth

A

Fossils and rocks can be carbon dated, the oldest rock found being 4.3b years old suggesting the Earth is at least 4.6b years old

25
Q

Evidence organisms have evolved

A

Fossils demonstrate different life forms. Comparative anatomy shows the similarities differences between species, particularly their bone structure. Comparative embryology has shown that all vertebrates develop similarly and are believed to have a common ancestor

26
Q

How fossils provide evidence how animals have developed

A

Fossils provide evidence organisms from the past are not the same as today and show a clear progression in features

27
Q

How absolute dating ca be used to date fossils

A

Carbon-14 is an isotope which decomposes after the death of a life form. The prevalence of this isotope indicates how long they have been dead for

28
Q

Distinguish between evolution and natural selection

A

Evolution: Gradual change in the traits of a population because of advantageous mutations
Natural selection: Members of a population with superior traits survive

29
Q

Importance of variation and how variation occurs

A

Variation shuffles the genetic material being spread and without variation, evolution does not occur. Variation can occur by random mating and mutations

30
Q

Outline the Theory of Natural Selection and use specific examples

A

The Theory of Natural Selection outlines how only the animals with the traits best suited to their environment will survive to reproduce, expanding their population, whereas animals that cannot cannot reproduce and will die. Some bacteria have grown resistant to antibiotics demonstrating how they have adapted to the environment. Insects are similarly resistant to pesticides which allows them to survive

31
Q

How does recombinant DNA, gene therapy and stem cells improve our understanding of biology?

A

Recombinant DNA uses enzymes and other lab techniques to isolate DNA segments. Gene therapy is when faulty genes are replaced in an attempt to cure disease or improve ability to fight disease. Stem cells are cells grown outside the body which can be then implanted

32
Q

Advantages and disadvantages with the use of biotech

A

Advantages: Allows humans to breed animals and crops which have advantageous characteristics, can help people (e.g. artificial insulin)

Disadvantages: Can promote monoculture, prevent natural processes such as natural selection, and we risk playing God

Biology + E&E (2 decks)

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