exam revision bio semester 2 Flashcards
(124 cards)
1
Q
homeostasis
A
homeostasis the maintenance
of a relatively stable internal
environment in the body
despite changes in the external
environment
2
Q
organism
A
a living thing made up
of one or more cells
3
Q
what is the cell theory
A
1 all living things are made up of cells
2 cells are the smallest and most basic units of life
3 all cells come from pre-existing cells.
4
Q
prokaryotes
A
a group of
single-celled organisms with no
nucleus and a circular loop of
DNA. Bacteria and archaea are
both prokaryotic
5
Q
eukaryotes
A
a group of
single-celled organisms with no
nucleus and a circular loop of
DNA. Bacteria and archaea are
both prokaryotic
6
Q
do eukaryotes have membrane bound organelles
A
yes
7
Q
do prokaryotes have membrane bound organelles
A
no
8
Q
what is the DNA organisation of eukaryotes
A
More than one linear strand of
DNA packaged in a chromosome
in a nucleus
9
Q
what is the DNA organisation of a prokaryotic cell
A
one circular chromosome and additional plasmids
10
Q
what are eukaryotic organisms nature
A
can be unicellular or multicellular
11
Q
what are prokaryotic organisms nature
A
unicellular
12
Q
what is the size of(roughly) of a eukaryotic cell
A
larger
13
Q
what is the size of(roughly) of a prokaryotic cell
A
smaller
14
Q
what is the method of cell replication for eukaryotic cells
A
Mitosis and meiosis
15
Q
what is the method of cell replication for prokaryotic cells
A
binary fission
16
Q
mitosis
A
mitosis the cell division phase
which involves the complete
separation of sister chromatids
and nuclei
17
Q
somatic cell
A
somatic cell any cell that is not a
reproductive cell (such as sperm
and egg cells). Somatic cells are
diploid (2n), meaning they contain
two sets of chromosomes – one
inherited from each parent
18
Q
difference between prokaryotic cells and eukaryotic cells
A
Prokaryotes are cells that lack a nucleus and membrane-bound organelles. They are smaller and simpler and include bacteria and archaea. Eukaryotic cells are cells that do have a nucleus and membrane-bound organelles, which help to organize and compartmentalize functions in the cell.
19
Q
what is the function of the nucleus
A
The nucleus is surrounded by a double membrane. Its role is to protect
and confine the genetic information (DNA) of the cell. Inside the
nucleus is a smaller structure known as the nucleolus which is the site of
ribosome production.
20
Q
what is the function of ribosomes
A
Ribosomes are tiny structures made of ribosomal RNA (rRNA) and
proteins that fold into a large and small subunit. Cells have many
ribosomes, which either float freely in the cytoplasm or are attached
to the rough endoplasmic reticulum. Ribosomes assemble the building
blocks to make proteins
21
Q
what is the function of the rough endoplasmic reticulum
A
A membranous chain of connected and flattened sacs which are
coated with ribosomes. This allows the rough endoplasmic reticulum
to synthesise and modify proteins. The rough endoplasmic reticulum
typically surrounds, or is close to, the nucleus
22
Q
what is the function of the smooth endoplasmic reticulum
A
A membranous chain of connected and flattened sacs which are
not coated with ribosomes. The smooth endoplasmic reticulum is
responsible for the production of lipids in a cell.
23
Q
what is the function of the Golgi apparatus
A
Stacked flattened sacs that are the sites of protein sorting, packaging, and
modification for use in the cell or export. Protein-filled vesicles often fuse
with or bud off from the Golgi apparatus. Also known as the Golgi body.
24
Q
what is the function of lysosomes
A
A membrane-bound vesicle that contains digestive enzymes. It is
responsible for breaking down cell waste and toxins, acting like a
garbage disposal
25
what is the function of the mitochondria
An organelle with a highly folded inner membrane surrounded by a
second outer membrane. Mitochondria are the site of aerobic cellular
respiration, a chemical reaction that produces the ATP required to power
cellular processes. They also contain their own DNA and ribosomes.
26
what is the function of chloroplast
A double membrane-bound organelle that contains flattened, fluid-filled
sacs that are the site of photosynthesis. Chloroplasts also contain their
own DNA and ribosomes.
27
what is the function of a vacuole
A membrane-bound sac that is used for water and solute storage.
Vacuoles can also play a role in maintaining plant cell structure.
28
what is the function of the plasma membrane
The plasma membrane is a selectively permeable barrier between
the intracellular and the extracellular environment. It is made of a
phospholipid bilayer which is studded with many molecules.
29
what is the function of a cell wall
A sturdy border outside the plasma membrane that provides strength
and structure to plant, bacterial, and fungal cells. (not in animals)
30
what is the function of a vesicle
A small, membrane-bound sac that transports substances into or out of a
cell, or stores substances within a cel
31
what is the function of a cytoskeleton
A large network of protein filaments that start at the nucleus and reach
out to the plasma membrane. The cytoskeleton is critical for maintaining
shape and transporting vesicles around the cell. In the given fluorescence
microscopy photo, the purple represents the cytoskeleton
32
organelles which are not membrane-bound
ribsomes
cell wall
cytoskeleton
33
two key difference between animal and plant organelles
Unlike plants, most animals have evolved structures like skeletons
that provide structural support for the organism. Plants rely on their
strong cell walls to perform the same function. these cell walls made of cellulose is present in plant cells but not
animal cells.
Chloroplasts are found in plants as they are the site of photosynthesis, which is how plants source glucose for energy. Animals source their food through other methods. Chloroplasts are present in plant cells but not animal cells.
34
what organelles do plants have that animals do not
-chloroplast
-cell wall
35
what is a gene
gene a section of DNA that
carries the code to make a protein
36
what is a genome
genome the complete set of
DNA contained within an
organism’s chromosomes
37
what are alleles
alleles, which are different forms of the same gene but with small differences in
their base sequence.
38
what is the distinction between genes, genome and alleles
Genes are DNA segments that code for traits, while alleles are different versions of a gene. The genome is the complete set of genetic material in an organism, including all genes and alleles.
39
the nature of a pair of homologous chromosomes carrying the same loci
A pair of homologous chromosomes consists of two chromosomes, one inherited from each parent, that carry the same gene loci (specific positions of genes). While the genes at these loci are the same, the alleles (versions of the gene) may differ between the chromosomes. Homologous chromosomes are similar in size, shape, and genetic content but may carry different variants of genes (alleles).
40
explain autosomal chromosomes
Autosomes are the non-sex chromosomes, present in pairs in both males and females, and carry most of an organism's genetic information. In humans, there are 22 pairs of autosomes.
41
explain sex chromosomes
Sex chromosomes determine an individual's biological sex and are different in males and females. In humans, females have two X chromosomes (XX), while males have one X and one Y chromosome (XY). The sex chromosomes carry genes that influence sexual development and reproduction
42
difference between sex chromosomes and autosomal chromosomes
Autosomes are non-sex chromosomes that carry most of an organism's genetic information and are the same in both sexes, while sex chromosomes determine biological sex and differ between males (XY) and females (XX).
43
how many chromosomes are present in humans
Human somatic cells mostly contain
46 chromosomes and therefore have a diploid number of 2n = 46.
44
explain chromosome size of humans compared to others
chromosome size can also vary greatly; for instance, human chromosomes are much larger in size compared to those of some other species like bacteria, which have a single, much smaller circular chromosome.
45
define karyotypes
a visual representation
of an individual’s entire genome
organised into homologous pairs
46
what is the purpose of a karyotype
When reading
karyotypes, scientists will check that the correct number of chromosomes are present and
that the size and length of each chromosome are correct. This information is used to check for possible genetic abnormalities. Can also be used to determine the species of the organism
47
What is meiosis?
Meiosis is the process of cell division that reduces a diploid cell (2 sets of chromosomes) to haploid gametes (1 set of chromosomes). It produces four genetically unique haploid cells (sperm or eggs).
48
How does meiosis affect chromosome number?
Meiosis reduces the chromosome number from diploid (two sets of chromosomes) to haploid (one set of chromosomes), ensuring that offspring have the correct chromosome number after fertilization.
49
What is crossing over, and why is it important?
Crossing over is the exchange of genetic material between homologous chromosomes during prophase I of meiosis. It creates new combinations of alleles, contributing to genetic diversity.
50
What is independent assortment, and how does it contribute to genetic diversity?
Independent assortment occurs during metaphase I when homologous chromosomes align randomly at the cell's equator. This random distribution of chromosomes to daughter cells leads to genetic variation in gametes.
51
How does meiosis contribute to genetic diversity?
Meiosis generates genetic diversity through crossing over and independent assortment, leading to unique combinations of genes in offspring, enhancing variability in a population.
52
What is the difference between diploid and haploid cells?
Diploid cells have two sets of chromosomes (one from each parent), while haploid cells have only one set of chromosomes. Gametes are haploid and are produced through meiosis.
53
aneuploidy
aneuploidy when a cell or
organism varies in the usual
number of chromosomes in its
genome by the addition or loss
of a chromosome
54
polypoidy
polyploidy when an organism
contains additional sets of
chromosomes in its genome
55
monosomy
monosomy a genetic abnormality
where an organism has one
missing chromosome
56
trisomy
trisomy a genetic abnormality
where an organism has one
extra chromosome
57
What is a dominant allele, and how does it affect an organism's phenotype?
A dominant allele is an allele that expresses its trait even when only one copy is present in a genotype. It masks the effect of the recessive allele in a heterozygous individual.
58
What is a recessive allele, and when does its phenotype appear in an organism?
A recessive allele only expresses its trait when an individual inherits two copies of the recessive allele (homozygous recessive). Its trait is masked by the dominant allele in a heterozygous individual.
59
What genotype would a person have if they exhibit a dominant phenotype for a trait that follows Mendelian inheritance patterns?
The genotype would be either homozygous dominant (AA) or heterozygous (Aa), since the dominant allele is expressed in both cases
60
How does a homozygous genotype differ from a heterozygous genotype?
A homozygous genotype has two identical alleles for a trait (AA or aa), while a heterozygous genotype has two different alleles (Aa), with one being dominant and the other recessive.
61
What is codominance, and how does it affect the expression of traits?
Codominance occurs when both alleles in a heterozygous organism are fully expressed, leading to a phenotype that shows both traits equally. For example, in blood type inheritance, the A and B alleles are codominant, so a person with genotype AB will have both A and B antigens on their red blood cells.
62
What is an example of codominance in humans?
An example of codominance in humans is the inheritance of blood type AB. Both the A allele and the B allele are expressed equally in individuals with the AB genotype.
63
How does codominance differ from incomplete dominance?
n incomplete dominance, the heterozygous phenotype is a blend of the two alleles (e.g., red and white flowers producing pink offspring). In codominance, both alleles are fully expressed without blending (e.g., A and B blood types)
64
What would be the expected phenotypic ratio of offspring if two heterozygous individuals (Aa) for a dominant trait cross?
The expected phenotypic ratio would be 3 dominant phenotype : 1 recessive phenotype.
65
What would be the genotypic and phenotypic ratios of offspring from a cross between two heterozygous individuals (AB)?
Genotypic ratio: 1 AA : 2 AB : 1 BB
Phenotypic ratio: 1 A (homozygous) : 2 AB (codominant) : 1 B (homozygous)
66
What does it mean for an individual to be a carrier of a recessive trait?
A carrier is an individual who is heterozygous for a recessive trait (e.g., Aa). They carry one copy of the recessive allele but do not express the recessive phenotype.
67
How do genetic factors influence an organism's phenotype?
Genetic factors influence phenotype by providing the hereditary information encoded in the DNA. The specific alleles inherited from both parents determine traits such as eye color, height, and susceptibility to certain diseases.
68
In what ways can environmental factors influence an organism's phenotype?
Environmental factors, such as nutrition, temperature, light, and exposure to toxins, can impact the expression of genes and affect traits like body size, skin color (due to UV exposure), and leaf color in plants (due to light intensity).
69
What are epigenetic factors, and how do they affect phenotype?
Epigenetic factors refer to chemical modifications to DNA or histone proteins that alter gene expression without changing the underlying DNA sequence. These modifications can be influenced by environmental factors and can affect traits such as stress responses, memory, and even inheritance patterns in some cases.
70
Can epigenetic changes be passed down to future generations?
Yes, some epigenetic changes can be inherited. These changes can be passed down through generations if they affect the germ cells (egg or sperm). However, not all epigenetic modifications are permanent, and many are reset in the next generation.
71
What is the "nature vs. nurture" debate, and how does it relate to phenotype?
The "nature vs. nurture" debate concerns the relative contributions of genetic inheritance (nature) and environmental factors (nurture) in determining traits and behavior. Both factors play a role in shaping phenotype, and many traits result from the interaction of both genetic and environmental influences.
72
sexual reproduction
the fusion
of two distinct haploid gametes
to produce a single diploid zygote
composed of two sets
of chromosome
73
asexual reproduction
asexual reproduction producing
offspring without the fusion
of gametes
74
clone
a genetically identical
organism or section of DNA
75
binary fission
binary fission a type of
asexual reproduction where one
organism divides into two
identical organisms
76
budding
budding a type of asexual
reproduction where a group of
cells form a bud and break away
from the original organism to form
a clone
77
fragments
fragmentation a type of asexual
reproduction where a parent
organism breaks into fragments,
each of which may develop into
individual clones
78
vegetative propagation
vegetative propagation a type of
asexual reproduction where a plant
grows from fragments, such as
stem or root cuttings, of its parents
79
sporogenesis
sporogenesis a type of asexual
reproduction where spores form
on the surface of the organism
and are dispersed into the
surroundings where they may
develop into individual clones of
the original
80
clone
a genetically identical
organism or section of DNA
81
reproductive cloning
technologies artificially induced
human interventions to produce
genetically identical clones
82
somatic cell nuclear transfer
(SCNT)
somatic cell nuclear transfer
(SCNT) the transference of
a somatic cell nucleus into an
enucleated egg cell
83
steps of somatic cell transfer
Enucleation – the removal or destruction of the nucleus from the donated egg cell to produce an enucleated egg cell.
2 Extraction – the donated somatic cell’s nucleus is extracted.
3 Insertion – the somatic cell’s nucleus is inserted into the enucleated egg cell.
4 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.
84
embryo splitting
the division
of an early embryo into several
individual embryos
85
in-vitro fertilisation (IVF)
the fertilisation of an egg outside
of the body
86
plant grafting
the attachment of
two individual plant stems together
87
explain the process of embryo splitting
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.
88
What is genetic diversity, and why is it important for a species?
Genetic diversity refers to the variety of genetic material within a population or species. It is important because it enhances the ability of a population to adapt to changing environments, increases resistance to diseases, and helps ensure the survival of the species in the long term.
89
How does genetic diversity contribute to a population's ability to adapt to environmental changes?
Genetic diversity provides a pool of different alleles, some of which may be advantageous in new or changing environments. These genetic variations allow individuals with beneficial traits to survive and reproduce, passing those traits on to future generations, increasing the population's overall adaptability.
90
What are the risks of low genetic diversity within a population?
Low genetic diversity can make a population more vulnerable to disease outbreaks, environmental changes, and inbreeding. This can lead to a higher rate of genetic disorders, reduced fertility, and increased susceptibility to extinction, especially in small or isolated populations.
91
How does genetic diversity improve a population's resistance to diseases?
With genetic diversity, some individuals may carry alleles that provide resistance to specific diseases. This means that if a disease strikes, not all individuals will be equally affected, and some may survive and pass on the resistant genes to their offspring, helping the population recover.
92
What is the founder effect, and how does it impact genetic diversity?
the founder effect occurs when a small group of individuals establishes a new population. This new population may have reduced genetic diversity compared to the original population, potentially leading to inbreeding and a higher susceptibility to genetic disorders.
93
What is the bottleneck effect, and how does it affect genetic diversity?
The bottleneck effect occurs when a population undergoes a drastic reduction in size due to a catastrophic event (e.g., natural disaster or disease). This reduction leads to a loss of genetic diversity, which can limit the population's ability to adapt to future environmental challenges.
94
How does genetic drift affect genetic diversity in small populations?
Genetic drift refers to random changes in allele frequencies, especially in small populations. Over time, certain alleles may become more or less common by chance, reducing genetic diversity and potentially eliminating beneficial alleles from the population.
95
What role do mutations play in maintaining genetic diversity within a population?
Mutations introduce new genetic variations by altering DNA sequences. While most mutations may be neutral or harmful, some can provide beneficial traits that increase an organism's fitness, contributing to genetic diversity and the long-term survival of the population.
96
What are adaptations, and how do they contribute to an organism’s survival?
daptations are inherited traits or behaviors that enhance an organism’s ability to survive and reproduce in its environment. They increase an organism’s fitness by helping it better meet the challenges of its surroundings, such as obtaining food, avoiding predators, and reproducing.
97
What is a structural adaptation, and can you provide an example?
A structural adaptation is a physical characteristic or feature of an organism's body that helps it survive in its environment. For example, the thick fur of arctic animals like polar bears helps insulate them against cold temperatures.
98
What is a physiological adaptation, and how does it differ from structural adaptations?
A physiological adaptation is an internal or biochemical process that improves an organism’s ability to survive. Unlike structural adaptations, which are physical features, physiological adaptations involve functions like metabolic changes or how the body responds to environmental stress. An example is how desert animals like camels can conserve water in extreme heat.
99
What is a behavioral adaptation, and can you give an example?
A behavioral adaptation is an action or behavior that helps an organism survive in its environment. For example, migratory birds move to warmer climates during winter to access food and favorable living conditions, ensuring survival.
100
How do structural adaptations help plants survive in different environments?
Structural adaptations in plants include features like thick waxy coatings on leaves to reduce water loss in dry environments, or deep root systems that allow plants to access water deep in the soil. These adaptations help plants conserve water, protect against extreme temperatures, and ensure successful reproduction.
101
How do animals regulate their body temperature through physiological adaptations?
Animals have various physiological mechanisms to regulate body temperature. For example, mammals like humans sweat to cool down, while other animals, like desert reptiles, may have specialized behaviors (e.g., burrowing) or physiological processes (e.g., altering blood flow) to avoid overheating.
102
What is the difference between endothermic and ectothermic thermoregulation?
Endotherms (e.g., mammals and birds) regulate their body temperature internally through metabolic processes, while ectotherms (e.g., reptiles and amphibians) rely on external sources, such as the sun, to regulate their body temperature. This allows endotherms to maintain a stable internal temperature, while ectotherms must adjust their behavior according to environmental conditions.
103
How do behavioral adaptations enhance survival in predator-prey interactions?
Predator and prey species often develop behavioral adaptations to enhance survival. For example, prey species may develop behaviors like hiding or fleeing when threatened, while predators may use strategies such as stalking or hunting in groups to catch prey more effectively.
104
What is ecological interdependence, and why is it important in an ecosystem?
Ecological interdependence refers to the reliance of species on each other within an ecosystem for resources such as food, shelter, and pollination. This interdependence helps maintain ecosystem stability and balance by regulating populations and supporting biodiversity.
105
What is a keystone species, and how does it impact an ecosystem?
A keystone species is a species whose presence and role in an ecosystem have a disproportionately large effect on the structure and function of the environment. Even if they are not abundant, keystone species help maintain ecological balance. For example, sea otters control sea urchin populations, preventing overgrazing of kelp forests.
106
How do predators influence the size and density of prey populations?
Predators help regulate prey populations by controlling their numbers. By hunting and killing individuals, predators prevent prey species from becoming overabundant, which could lead to overgrazing or depletion of resources. This helps maintain balance within the ecosystem.
107
What happens when a keystone species is removed or declines in an ecosystem?
The removal or decline of a keystone species can lead to a dramatic shift in the ecosystem. It can cause a cascade of changes that affect many other species, disrupting the food chain and altering habitat structure. For example, the decline of sea otters has led to an increase in sea urchins, which overgraze kelp forests, causing ecosystem degradation.
108
explain interdependence in an ecosystem
species within an ecosystem are all independent, they all rely on each other.
if one species in removed any species that interacted with it would be affected.
109
define the interaction between species - interspecific
are between different species
110
define the interaction between species - infraspecific
interactions occur between individuals of the same species, more competition as they are the same species they have the same needs.
111
the interactions between species that can live together and have partnerships - symbiosis. define mutualism
partnership were both species benefit
112
the interactions between species that can live together and have partnerships - symbiosis. define commensalism
only one species benefits but the other is not harmed
113
the interactions between species that can live together and have partnerships - symbiosis. define parasitism
one species benefits and the other is harmed
114
the interactions between species that can live together and have partnerships - symbiosis. define amensalism
one species is impaired or damaged and The other is unaffected
115
interaction between species; predation
one animal (predator) kills and feeds on another (prey)
116
feeding interdependency; autotrophs
make their own energy from sunlight e.g. plants.
117
feeding interdependency; heterotrophs
obtain energy by eating other organisms
118
the population dynamic distribution of populations
Population distribution refers to how individuals are spread across a given area, influenced by factors like resources, climate, and social behaviors. It can be clumped, uniform, or random. Population dynamics study how these distributions change over time due to birth rates, death rates, and migration.
119
a test cross
when we mate an individual with another individual that has the recessive phenotype helping to determine if a dominant individual is homozygous or heterozygous
120
define density
the number of a given species per unit area
121
define abundance
the total number of organisms of a given species
122
why is measuring abundance important
conservation; measuring the abundance of populations of endangered species over time to decide if the populations are stable, increasing or decreasing. decreasing abundance leads to extinction
123
3 factors affecting population
-availabkle resources
-predation
-disease
124
