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Biology EXAM 8 > Biology 8 Exam > Flashcards

Biology 8 Exam Flashcards

1
Q

Q: What are the main functions of cell division?

A

Reproduction, growth, and repair.

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2
Q

How do unicellular organisms reproduce?

A

By cell division.

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3
Q

What two processes does cell division involve in eukaryotes?

A

Mitosis (division of the nucleus) and cytokinesis (division of the cytoplasm).

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4
Q

What is the difference between asexual and sexual reproduction?

A

Asexual reproduction involves a single parent producing genetically identical offspring, while sexual reproduction involves two parents and produces genetically unique offspring.

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5
Q

What type of cell division occurs in bacteria?

A

Binary fission.

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6
Q

What type of cell division produces human gametes?

A

Meiosis.

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7
Q

Why is DNA partitioned among chromosomes in eukaryotic cells?

A

DNA is partitioned among chromosomes to make it easier for the eukaryotic cell to replicate and distribute its large amounts of DNA during cell division.

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8
Q

What do chromosomes consist of, and how do they change during mitosis?

A

Chromosomes consist of chromatin, a complex of DNA and protein that condenses during mitosis. When chromosomes replicate, they form identical sister chromatids, which separate during mitosis to become the chromosomes of the new daughter cells.

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9
Q

What is binary fission, and how does it differ from mitosis?

A

Binary fission is the process of bacterial division, which is simpler and not the same as mitosis in eukaryotic cells.

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10
Q

What is asexual reproduction, and how does it occur in single-celled and multicellular organisms?

A

In asexual reproduction, a single individual passes copies of all its genes to its offspring, resulting in genetically identical offspring.

Single-celled organisms, such as bacteria, and multicellular organisms, like hydras, reproduce asexually. Hydras can reproduce by budding to form genetically identical offspring.

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11
Q

How does mitosis enable asexual reproduction?

A

Mitosis allows for asexual reproduction by producing cells that carry the same genetic information as the parent cells, making the offspring genetically identical to the parent.

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12
Q

How does sexual reproduction increase genetic variation compared to asexual reproduction?

A

Sexual reproduction produces greater genetic variation because offspring inherit a unique combination of genes from two parents, making them genetically distinct from both their parents and siblings.

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13
Q

What are human somatic cells, and how many chromosomes do they have?

A

Human somatic cells are diploid, meaning they have two sets of 23 chromosomes, for a total of 46 chromosomes.

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14
Q

What type of cell division occurs in the ovaries and testes, and what does it produce?

A

Meiosis occurs in the ovaries and testes, producing haploid gametes (eggs and sperm) that carry only one set of 23 chromosomes each.

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15
Q

What happens during fertilization in humans?

A

During fertilization, a haploid sperm cell combines with a haploid egg cell to form a diploid zygote with 46 chromosomes. This zygote develops into a sexually mature diploid adult.

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16
Q

What is the alternation of diploid and haploid stages in sexual life cycles?

A

In sexual life cycles, diploid organisms produce haploid gametes through meiosis, and fertilization produces diploid zygotes, maintaining the alternation between diploid and haploid stages.

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17
Q

What are the main stages of mitosis, and how do they alternate with interphase in the cell cycle?

A

prophase, metaphase, anaphase, and telophase, followed by cytokinesis. Mitosis alternates with interphase, which includes the G1, S, and G2 phases. DNA replication occurs during the S phase.

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18
Q

What is the mitotic spindle, and what is its function?

A

The mitotic spindle is an apparatus of microtubules that controls chromosome movement during mitosis, ensuring proper distribution to daughter cells.

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19
Q

What is the role of centrosomes and centrioles in mitosis?

A

Centrosomes, which include centrioles in animal cells, are organelles that help organize the mitotic spindle during cell division.

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20
Q

What happens to chromatids during metaphase and anaphase?

A

During metaphase, chromatids align at the metaphase plate, and during anaphase, sister chromatids separate and move toward opposite poles of the cell.

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21
Q

How do kinetochore microtubules and motor proteins function during anaphase?

A

Kinetochore microtubules, with the help of motor proteins, shorten to pull chromatids to opposite poles. Nonkinetochore microtubules slide past each other, elongating the cell.

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22
Q

How does cytokinesis differ between animal and plant cells?

A

In animal cells, cytokinesis occurs through the formation of a cleavage furrow that pinches the cell in two. In plant cells, a cell plate forms to divide the cytoplasm and create two daughter cells.

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23
Q

What is contained within the cytoplasm of a cell in late interphase?

A

Two centrosomes, each with centrioles, and chromosomes in the nucleus as loose chromatin. Nucleoli are also present.

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24
Q

What are the five phases of mitosis?

A

prophase, prometaphase, metaphase, anaphase, and telophase.

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25
What happens to chromatin fibers during prophase?
The chromatin coils into chromosomes, each made of two sister chromatids.
26
What initiates the formation of the mitotic spindle?
Microtubules grow out from centrosomes to form the spindle.
27
What is the metaphase plate?
It’s an imaginary line in the middle of the cell where chromosomes align.
28
What event marks the beginning of anaphase?
The centromeres split, separating the sister chromatids.
29
What happens to the spindle microtubules during anaphase?
Spindle microtubules pull chromosomes to opposite sides, and the cell stretches out.
30
What reforms around the chromosomes during telophase?
Nuclear envelopes form around the chromosomes at each pole
31
How does cytokinesis differ between animal and plant cells?
In animal cells, a cleavage furrow pinches the cell in two. In plant cells, a cell plate forms to separate the two cells.
32
What is binary fission?
It’s the simple cell division in bacteria, where the cell splits in two.
33
What drives the cell cycle?
Proteins called cyclins and Cdks control the timing of the cell cycle.
34
What are cyclins?
Cyclins are proteins whose levels rise and fall during the cell cycle.
35
What do cyclin-dependent kinases (Cdks) do?
Cdks are enzymes that need cyclins to be active and help move the cell through different stages.
36
What is the role of the anaphase-promoting complex (APC)?
The APC helps separate sister chromatids and destroys cyclins to end mitosis.
37
What happens as G1-cyclins rise?
G1-cyclins bind to their Cdks, signaling the cell to prepare chromosomes for replication.
38
What does the S-phase promoting factor (SPF) do?
SPF, which includes cyclin A and Cdk2, enters the nucleus to prepare the cell for DNA duplication and centrosome replication.
39
What occurs during DNA replication in terms of cyclins?
Cyclin E is destroyed, and the levels of mitotic cyclins increase during G2.
40
What does the M-phase promoting factor (MPF) initiate?
MPF initiates the assembly of the mitotic spindle, breakdown of the nuclear envelope, and condensation of chromosomes.
41
What does MPF activate at metaphase?
MPF activates the anaphase promoting complex (APC).
42
What role does the APC play in cell division?
The APC allows sister chromatids to separate during anaphase and destroys mitotic cyclins, starting the next cycle with G1 cyclin synthesis.
43
What is the purpose of checkpoints in the cell cycle?
Checkpoints monitor the cell cycle to stop it if something goes wrong.
44
What does the S phase checkpoint monitor?
It checks for the presence of Okazaki fragments during DNA replication before the cell can continue.
45
Where do DNA damage checkpoints occur?
DNA damage checkpoints occur before entering S phase (G1), during S phase, and after DNA replication (G2).
46
What do spindle checkpoints detect?
They detect issues with spindle fibers not attaching to kinetochores, blocking the cell from entering anaphase (M checkpoint).
47
What happens if there is improper spindle alignment?
The cell will block cytokinesis and may trigger apoptosis if the damage is severe.
48
What is the consequence of mutations in checkpoint proteins?
Mutations can lead to cancers since they allow damaged cells to continue dividing.
49
What is the role of checkpoints in the cell cycle?
Checkpoints monitor the cell cycle and can stop it if something goes wrong.
50
What does the S phase checkpoint monitor?
It checks for Okazaki fragments during DNA replication and won't allow the cell to continue until they are gone.
51
What do spindle checkpoints do?
They detect problems with spindle fibers not attaching to kinetochores and can halt the cell cycle at metaphase (M checkpoint).
52
Where are DNA damage checkpoints located?
They are found before S phase (G1), during S phase, and after DNA replication (G2)
53
How does the spindle checkpoint ensure proper attachment?
They detect problems with spindle fibers not attaching to kinetochores and can halt the cell cycle at metaphase (M checkpoint).
54
What happens if there is improper spindle alignment?
The cell blocks cytokinesis and may trigger apoptosis if the damage is severe and cannot be repaired.
55
Why are mutations in checkpoint proteins concerning?
Mutations can lead to cancers because they allow damaged cells to keep dividing instead of stopping.
56
What does growth factor depletion explain?
It explains density-dependent inhibition, where crowded cells stop dividing.
57
What is anchorage dependence?
It means that most animal cells need to be attached to a surface (like the extracellular matrix) to divide.
58
What is anchorage dependence?
It means that most animal cells need to be attached to a surface (like the extracellular matrix) to divide
59
How do cancer cells differ from normal cells in terms of division?
Cancer cells do not follow the normal rules; they can divide uncontrollably and do not exhibit density or anchorage dependence.
60
What are some characteristics of cancer cells?
They are often undifferentiated (unable to perform specific functions) and have properties similar to embryonic stem cells, like immortality and mobility.
61
What is a malignant tumor?
A malignant tumor invades surrounding tissues and can spread (metastasize) to other parts of the body.
62
What does it mean for cancer cells to be "immortal"?
It means they do not undergo programmed cell death like normal cells, which typically divide only 50-60 times before aging and dying.
63
What are carcinogens?
Carcinogens are agents that can cause cancer, such as UV light, radiation, cigarette smoke, certain viruses, and some food additives.
64
How can personal lifestyle affect cancer risk?
Your lifestyle choices can increase exposure to carcinogens, which may raise the risk of certain types of cancer.
65
How do offspring acquire genes from their parents?
Offspring inherit genes from their parents by receiving chromosomes.
66
What is genetics?
Genetics is the study of heredity and the variation of genes.
67
What is the specific location of a gene on a chromosome called?
The specific location of a gene is known as its locus.
68
What is asexual reproduction?
Asexual reproduction is when a single individual produces offspring by passing on copies of all its genes
69
Give an example of asexual reproduction.
An example is hydra, which can reproduce by budding to create genetically identical individuals.
70
How does mitosis contribute to asexual reproduction?
Mitosis allows organisms to reproduce asexually by creating cells that are genetically identical to the parent cells
71
What is the difference between asexual and sexual reproduction in terms of genetic variation?
Sexual reproduction produces greater genetic variation, while asexual reproduction creates genetically identical offspring.
72
How do offspring inherit genes in sexual reproduction?
Each offspring inherits a unique combination of genes from two parents, making them different from their siblings and parents.
73
What process occurs in the ovaries and testes to produce gametes?
Meiosis occurs in the ovaries and testes to produce haploid gametes (eggs and sperm).
74
How many chromosomes do haploid gametes carry?
Haploid gametes carry one set of 23 chromosomes each.
75
What happens during fertilization?
Fertilization combines an egg and a sperm, producing a diploid zygote with 46 chromosomes.
76
What is a diploid zygote?
A diploid zygote is the fertilized egg that contains two sets of chromosomes (one from each parent).
77
How does the life cycle progress after fertilization?
The zygote develops into a sexually mature diploid adult, which then produces haploid gametes.
78
What is the relationship between diploid and haploid stages in sexual life cycles?
Sexual life cycles involve alternating between diploid (two sets of chromosomes) and haploid (one set of chromosomes) stages.
79
How many chromosomes do normal human somatic cells have?
Normal human somatic cells have 46 chromosomes.
80
What two processes alternate in sexual life cycles?
Fertilization and meiosis alternate in sexual life cycles.
81
What is a karyotype?
A karyotype is an ordered display of an individual’s chromosomes, often prepared using lymphocytes.
82
How many pairs of chromosomes are shown in a human karyotype?
A human karyotype shows 23 pairs of chromosomes.
83
What are homologous chromosomes?
Homologous chromosomes are pairs of chromosomes that have the same length, centromere position, and staining pattern, and usually carry genes for the same inherited characters.
84
How are the 23 pairs of chromosomes categorized in humans?
In humans, there are 22 pairs of autosomes and 1 pair of sex chromosomes.
85
How do we inherit chromosomes?
We inherit one chromosome of each homologous pair from each parent.
86
What are sex chromosomes, and what is the exception in humans?
Sex chromosomes determine an individual's sex. In humans, females have a homologous pair of X chromosomes (XX), while males have one X and one Y chromosome (XY). The Y chromosome has fewer corresponding genes compared to the X chromosome.
87
What do sperm cells and ova (gametes) contain?
Sperm cells and ova each have one set of chromosomes, consisting of 22 autosomes and either an X or a Y chromosome.
88
What is a haploid cell?
A cell with a single set of chromosomes is called haploid
89
What is the haploid number of chromosomes for humans?
The haploid number of chromosomes for humans is 23 (n = 23).
90
What happens during fertilization?
A haploid sperm fuses with a haploid ovum, forming a fertilized egg (zygote) that contains two haploid sets of chromosomes.
91
What is the chromosome count for a diploid cell?
The diploid number of chromosomes for humans is 46 (2n = 46).
92
What are the only haploid cells in sexual reproduction?
The only haploid cells in sexual reproduction are gametes, produced by meiosis.
93
How does the timing of meiosis and fertilization vary?
The timing of meiosis and fertilization varies among species, but the life cycle of humans and other animals is typical of one major type.
94
What is the role of gametes in reproduction?
Gametes fuse to form a diploid zygote, which divides by mitosis to create a multicellular organism.
95
What characterizes the life cycle of most fungi and some protists?
The zygote is the only diploid stage. It undergoes meiosis to create haploid cells, which then develop into haploid multicellular adults
96
How do plants and some algae reproduce?
They have a life cycle with both haploid (gametophyte) and diploid (sporophyte) stages. Spores from the sporophyte become gametophytes, which produce gametes.
97
How does sexual reproduction create genetic diversity?
It introduces variation through independent assortment, crossing over, random fertilization, and mutations.
98
What is independent assortment?
It's the random arrangement of chromosomes during meiosis, leading to different combinations in gametes.
99
How many combinations can arise from independent assortment in humans?
With 23 chromosomes (n = 23), humans can have about 8 million combinations due to independent assortment.
100
What is crossing over? A7: Crossing over occurs when?
Crossing over occurs when homologous chromosomes exchange genetic material, creating new combinations of genes.
101
What is crossing over?
It's when chromosomes swap DNA segments during meiosis, mixing traits from parents.
102
Why is crossing over important?
It creates genetic variety in offspring.
103
How often does crossing over happen in humans?
It occurs 2 to 3 times for each pair of chromosomes.
104
What is random fertilization?
It's when any sperm can combine with any egg, making each zygote unique.
105
How many combinations can a human zygote have?
A human zygote can have about 70 trillion possible combinations.
106
What do mutations do?
Mutations add new genetic variations to a population.
107
What is the main job of meiosis?
Meiosis reduces chromosomes from 46 to 23 and produces four daughter cells.
108
How is meiosis different from mitosis?
Meiosis includes chromosome pairing and crossing over, while mitosis does not.
109
What happens during prophase I of meiosis?
Homologous chromosomes pair up and exchange genetic material.
110
What occurs during anaphase I?
The pairs of chromosomes separate and move to opposite ends of the cell.
111
What do the two divisions of meiosis produce?
They produce four haploid daughter cells from one diploid cell.
112
What occurs in prophase I of meiosis?
Each chromosome duplicates and pairs with its homolog, forming sister chromatids. This is when crossing over can occur, allowing genetic material exchange.
113
What occurs in telophase I?
Two daughter cells form, each with one chromosome from each homologous pair.
114
Describe anaphase I.
Homologous chromosomes separate, but sister chromatids remain together and move to opposite poles of the cell
114
What happens during metaphase I?
Homologous chromosomes align at the equatorial plate of the cell.
115
Is there DNA replication before prophase II?
No, DNA does not replicate before prophase II
116
What happens during metaphase II?
Chromosomes line up at the equatorial plate again, similar to metaphase in mitosis.
117
Describe anaphase II.
The centromeres divide, and sister chromatids move to opposite poles.
118
What is the result of telophase II?
Four haploid daughter cells are formed, each genetically different from the parent cell.
119
Where does mitosis occur?
Mitosis occurs in body cells.
120
Where does meiosis take place?
Meiosis occurs in reproductive organs.
121
How many division events occur in mitosis?
Mitosis has one division event.
122
How many division events occur in meiosis?
Meiosis has two division events.
123
What is the result of mitosis in terms of daughter cells?
Mitosis produces two daughter cells that are diploid (2N) and identical to the parent.
124
What is the result of meiosis in terms of daughter cells?
Meiosis produces four daughter cells that are haploid (N) and genetically different from the parent.

Biology EXAM 8 (1 decks)

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