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Biology Unit 2 > Reproduction > Flashcards

Reproduction Flashcards

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AP® Biology flashcards
1
Q

define population

A

a group of individuals of the same species living in the same location

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2
Q

define gene pool

A

the total number of alleles within a particular population

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3
Q

define gene

A

a section of DNA that carries the code to make a protein

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4
Q

define allele

A

alternate forms of a gene

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5
Q

what is genetic diversity?

A

The genetic diversity of a population refers to the amount of genetic variation that exists between individuals.

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6
Q

how is genetic diversity measured?

A

This is measured by the population’s gene pool (sum of all the different genes and alleles that are present in a particular population).

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7
Q

what does a larger or more diverse gene pool contain?

A

A larger or more diverse gene pool contains a greater variety of different genes and alleles, meaning the population will have a greater variety of genotypes and phenotypes.

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8
Q

what is the gene pool of a population influenced?

A

The gene pool of a population is influenced and maintained by a number of naturally occurring mechanisms, including mutations, genetic drift, gene flow and natural selection.

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9
Q

Why is genetic diversity important?

A

Genetic diversity is vitally important in protecting the longevity of a species by guarding against disadvantageous environmental changes, like new diseases or predators.

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10
Q

what does a larger gene pool mean for change?

A

The larger the gene pool, the greater that population’s resilience to environmental change.
This is because populations with greater numbers of alleles are more likely to contain alleles that are already well adapted to survive the new environmental challenges.

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11
Q

define Sexual reproduction

A

the fusion of two distinct haploid gametes (fertilisation) to produce a single diploid zygote composed of two sets of chromosomes

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12
Q

define Reproductive strategies

A

adaptations to reproduction that improve the success of survival of a species

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13
Q

define Fertilisation

A

the process by which two gametes (such as sperm and egg cells) fuse and form a zygote

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14
Q

define Zygote

A

the diploid cell formed by the combination of two haploid gamete cells

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15
Q

define Angiosperms

A

flowering plants with stems, roots and leaves

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16
Q

define pollination

A

a form of sexual reproduction in the plants that involves the fusion of pollen (male gamete) and ovule (female gamete) and leads to the production of seeds

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17
Q

when does sexual reproduction occur?

A

Sexual reproduction occurs is almost all eukaryotes, including animals and plants.

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18
Q

what can reproduce sexually?

A

Up to 99% of eukaryotic organisms can reproduce sexually, including most plants and animals.

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19
Q

are their different methods of sexual reproduction?

A

There are many different methods of sexual reproduction, each of which have evolved over time due to the environmental pressures facing the species (e.g. resource availability and predation).

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20
Q

how are these sexual reproduction methods classified?

A

These methods are thought of as differences in reproductive strategies rather than in animal categories, as organisms within the same broad category, e.g. insects or fish, can show huge variation in how they reproduce.

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21
Q

what are differences in sexual reproduction strategies?

A

This includes factors such as the location of embryonic development, the number of offspring produced per reproductive cycle and the amount of parental care invested in each offspring.

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22
Q

how can sexually reproducing animals be classified?

A

oviparous - eggs released into external environment and embryo develops through nutrients in the yolk
viviparity - embryo develops inside mothers body

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23
Q

how many species of plants are there?

A

Estimated that there are roughly 400 000 different species of plants currently known to science.

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24
Q

how many plants use pollination?

A

Around 90% of these are flowering plants (angiosperms), which reproduce via pollination.

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25
Q

when does pollination occur?

A

Pollination occurs when pollen (male gamete) is collected by the stigma of the flower and fuses with the ovule (female gamete).
From here, the embryo that develops will become a seed, which contains nutrients from which an immature plant can grow into a new plant under the right conditions.

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26
Q

what does pollen transfer rely on?

A

Pollen transfer in plants typically replies on a pollinator to move pollen from one plant to another.

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27
Q

These pollinators can be:

A

Biotic - living organisms (e.g. insects or birds) that are attracted to the brightly coloured petals, inviting smell and nutrient-rich nectar.
Abiotic - non-living methods (e.g. wind or water)

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28
Q

advantages of sexual reproduction

A
  • increases genetic diversity of a population by allowing for recombinant offspring
  • improving disease resistance by promoting the presence of different alleles
  • combining the genetic material from two gametes reduces the chances of an offspring inheriting a genetic disorder that might be carried by one parent
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29
Q

disadvantages of sexual reproduction

A
  • the cost of male progeny
  • the time, energy, and resources it takes to attract and find a mate
  • the risk of transferable diseases associated with sexual intercourse
  • the risk of losing offspring to outside influences such as embryo damage
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30
Q

define Asexual reproduction

A

producing offspring without the fusion of gametes

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31
Q

define Clone

A

a genetically identical organism or section of DNA

32
Q

define Binary fission

A

a type of asexual reproduction where one organism divides into two identical organisms

33
Q

define spores

A

small haploid units used as a means of asexual reproduction in sporogenesis

34
Q

What is asexual reproduction?

A

Some organisms can reproduce without the fusion of gametes, and therefore do not require a mate.
The offspring or daughter cells are clones of each other and of the parent.
Usually only occurs in unicellular and simple multicellular organisms.

35
Q

Types of asexual reproduction include

A

Binary fission
Budding
Fragmentation
Vegetative propagation
Sporogenesis
Parthenogenesis

36
Q

most common form of asexual reproduction?

A

The most common form a asexual reproduction is known as binary fission.

37
Q

features of binary fission?

A

This occurs most commonly in simple prokaryotic organisms (e.g. bacteria).
Similar form of binary fission also occurs in more complex organisms such as polyps, where the organism splits into two equally sized clones.

38
Q

what organisms does budding usually occur in?

A

Typically occurs in simple eukaryotes such as, yeast, sponges, jellyfish, coral and worms.

39
Q

what is budding?

A

Involves the formation of a bud, which forms due to increased cell growth and then breaks away from the main organism where it can then develop into an entirely separate organism.
This new organism will have identical DNA to the original organism.

40
Q

what organisms does fragmentation usually occur in?

A

Typically occurs in simple eukaryotes such as worms, sea stars and many species of plants.

41
Q

what is fragmentation?

A
  • Involves a parent organism breaking into separate fragments, each of which is capable of independently developing into a new, separate organism that is identical to the original.
  • The breaking away of fragments may or may not be intentional and will involve regrowth of the parent organism to account for the lost fragments.
42
Q

what is Vegetative propagation?

A
  • Type of asexual reproduction that allows a plant to reproduce without the need for seeds.
  • Involves a vegetative section of the plant, such as the roots or leaves, breaking away from the original plant and then independently growing into a new plant.
  • This breakaway section is called a ‘cutting’.
43
Q

what organisms does sporogenesis usually occur in?

A

Typically occurs in fungi, algae, moulds and many plants.

44
Q

what is sporogenesis?

A

Involves the formation of spores, which are small haploid units that form on the surface of the organism and are dispersed into the surroundings, often via water or air.
They can then grow into a larger, multicellular, haploid organism (known as a sporeling).

45
Q

what is Parthenogenesis?

A
  • Rarer form of asexual reproduction where an embryo can develop from a female gamete alone, without the need for a male gamete to fertilise it.
  • This process is sometime called ‘virgin birth’.
  • Results in eggs that are produced via mitosis and develop into a new organism that is identical to the female parent.
  • This is extremely rare and occurs in less than 0.1% of all vertebrate species.
46
Q

advantages of asexual reproduction?

A
  • asexually reproducing populations grow faster than sexually reproducing populations
  • offspring are identical clones of the parent, this is especially important for organisms that have adapted a phenotype that is fine-tuned to survive in a particular environment
  • requires very little parental investment and removes the need to protect fragile offspring
47
Q

disadvantages of asexual reproduction

A
  • genetic diversity is low and asexually reproducing populations may suffer during rapid environmental change, more susceptible to disease
48
Q

define Reproductive cloning technologies

A

artificially induced human interventions to produce genetically identical clones

49
Q

define Somatic cell nuclear transfer (SCNT)

A

the transference of a somatic cell nucleus into an enucleated egg cell

50
Q

define Enucleated

A

a cell that has had its nucleus removed or destroyed

51
Q

define Embryo splitting

A

the division of an early embryo into several individual embryos

52
Q

define in-vitro fertilisation (IVF)

A

the fertilisation of an egg outside of the body

53
Q

Reproductive cloning technologies in animals include:

A
  • Somatic cell nuclear transfer (SCNT)
  • Embryo splitting
54
Q

are their issues reproductive cloning technologies in animals?

A

Despite the success of animal reproductive cloning techniques, they are still complicated by ethical issues that must be considered.

55
Q

what does Somatic cell nuclear transfer (SCNT) result in?

A

In this process, the offspring produced is genetically identical to the donated somatic cell as they both contain the same nucleus and genetic material.

56
Q

what cells do somatic cell nuclear transfer (SCNT) involve?

A

a donated egg cell and a donated somatic cell from another animal

57
Q

The stages of SCNT include:

A

Enucleation - the removal or destruction of the nucleus from the donated egg cell to produce an enucleated egg cell.
Extraction - the donated somatic cell’s nucleus is extracted.
Insertion - the somatic cell’s nucleus is inserted into the enucleated egg cell.
Development - following insertion, the cell begins to divide and develop into an embryo, which is then implanted into a surrogate mother. The pregnancy then continues as normal.

58
Q

Applications of SCNT?

A
  • Primarily used to clone a variety of living and recently deceased animals (e.g. sheep, dogs and monkeys).
  • Most famous is Dolly the sheep (first mammal cloned using SCNT in 1997).
  • Researchers are investigating ways to revive extinct species using SCNT.
  • SCNT also has applications in the medical field (e.g. therapeutic cloning).
  • SCNT is a relatively new technology and still has much room for improvement, as such, there are a few unresolved issues surrounding the use and application of SCNT.
59
Q

Complications surrounding the use of SCNT?

A

Animal suffering - SCNT attempts are often unsuccessful, producing non-viable embryos or resulting in miscarriage during pregnancy. Animals that survive birth often suffer from severe developmental abnormalities. Life expectancy of cloned animals is far shorter than non-cloned offspring.

Human cloning - Application of SCNT in humans is illegal in many countries, including Australia. Arguments against the use of SCNT in humans include opposition to the mass destruction of egg cells and embryos from failed attempts, as well as, issues surrounding the unethical sourcing of eggs.

Premature aging - Although sheep from the same species as Dolly typically survive for up to 12 years, Dolly was euthanized after only 6 years when she developed a severe lung infection. She also developed arthritis, a disease that becomes more common with old age. Due to this many scientists believe that clones age at a greater rate due to the shortening of telomeres.

60
Q

features of embryo splitting?

A
  • Typically after the successful fertilisation of an egg cell, the cell begins to divide, forming an embryo and then an entire organism.
  • However, if an embryo is split during the early stages of embryonic development, each individual section will develop as an independent embryo.
  • This makes it possible to produce two or more genetically identical offspring.
  • While this process naturally occurs in the production of identical twins in humans, embryos are often artificially split for agricultural applications.
61
Q

The process of embryo splitting?

A
  • Egg and sperm cells are chosen and fertilised in a laboratory.
  • Early embryo is split. Ideally this occurs when the cluster of cells is between 6 - 8 cells, as at this stage the cells are still totipotent (capable of developing into viable embryos).
  • Split embryos are implanted into surrogate mothers where embryonic development is completed.
  • Each individual produced is genetically identical to the original embryo.
62
Q

Applications of embryo splitting

A

In agriculture, embryo splitting is often conducted in combination with in-vitro fertilisation (IVF) where scientists can selectively choose eggs and sperm from parents with desirable traits and fertilise them in a laboratory. (to produce favourable traits)

63
Q

Complications surrounding the use of embryo splitting?

A

Alteration of embryos - Some believe that embryo alteration is acceptable, and others argue that embryos are sacred and should never be altered.

Genetic diversity - By producing genetically identical offspring, the genetic diversity of a population is decreased. This decrease can potentially leave the population more susceptible to disease and environmental changes.

Research animals - Ability to produce large numbers of cloned animals could lead to the commercialisation and objectification of research animals, where animals are treated more as objects than living beings.
These animals may then be subjected to increased levels of abuse and mistreatment. Additionally, research animals with higher levels of cognitive functioning may be used, which are more conscious of the actions of researchers, causing them to experience more stress than an animal with less cognitive awareness.

64
Q

define Plant tissue culturing

A

the cloning of plant cells on a nutrient culture medium in a controlled environment

65
Q

define Callus

A

a mass of plant cells

66
Q

define Plant cutting

A

the growth of plants using a fragment of the original plant

67
Q

define Plant grafting

A

the attachment of two individual plant stems together

68
Q

define Scion

A

the upper stem of a plant used in grafting

69
Q

define Rootstock

A

the lower stem of a plant with a well-developed root system

70
Q

process of Plant tissue culturing?

A
  • Plant tissue culturing, or micropropagation, involves the cloning of plant cells in a controlled environment.
  • Plant cells, which can be obtained from a leaf, shoot or stem, are grown on a nutrient culture medium in sterile conditions, where lighting, temperature, hormone availability and nutrient availability are closely regulated.
  • As the tissue culture develops, a callus begins to form.
  • The callus can then be separated into several cultures and stimulated to grow into clones of the original plant.
71
Q

Applications of plant tissue culturing?

A
  • Environment of plants produced from plant tissue cultures is closely monitored and regulated.
  • Therefore, plant tissue cultures can be used to produce plants all year round in a disease-free environment.
  • Applications also include the production of clones for agricultural research.
  • Allows conservation groups to clone rare and endangered plant to save them from extinction.
72
Q

how are plant cuttings obtained and process?

A

Plant cuttings are obtained by cutting off a fragment of a plant such as a leaf, stem or root.
This plant cutting can be planted in soil or water.
Under the correct conditions, the cutting will grow producing a clone of the original plant.

73
Q

process of plant grafting?

A
  • Plant grafting involves attaching the stem of one plant (the scion) to the stem of another plant with an already developed root system (the rootstock).
  • Eventually, the two sections of the individual plants will grow and fuse together.
  • This produces a clone of the plant from which the scion was taken.
74
Q

Applications of cutting and grafting?

A
  • Compared to other plant cloning technologies, cutting and grafting are relatively old cloning techniques.
  • Both techniques allow for the rapid growth of a desired plant.
  • Grafting can often help provide plants with cold tolerance, resistance to disease and increased productivity.
75
Q

Biological implications of plant cloning?

A
  • Unrestrained cloning in plants could lead to a reduction in genetic diversity.
  • A cloned population of plants is more susceptible to disease, pests and environmental change than a natural population with high genetic diversity.

Biology Unit 2 (3 decks)

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