In a population, what describes the number of different alleles present for genes within that population?
Genetic diversity
High genetic diversity increases the range of traits present in a population.
Why does a population with higher genetic diversity have a greater potential to survive environmental change?
Greater range of alleles increases chance of advantageous traits.
Some individuals may already possess alleles suited to new conditions.
What evolutionary process causes populations to become better adapted to their environment over generations?
Natural selection
Individuals with advantageous traits reproduce more successfully.
Fill in the blank:
New alleles can arise when random ______ occur in DNA.
mutations
Mutations change nucleotide sequences and can create new alleles.
Why are most mutations unlikely to increase an organism’s chances of survival?
Most mutations are either harmful, or have no effect.
Many mutations disrupt protein structure or function.
How can a mutation sometimes increase reproductive success in a specific environment?
It produces an advantageous allele.
The allele may improve survival or reproductive success.
What must happen for a beneficial allele to spread through a population?
It must be inherited by offspring.
Natural selection acts on inherited genetic variation.
Fill in the blank:
Over many generations, an advantageous allele tends to ______ in frequency within a population.
increase
Individuals with the allele produce more offspring, some with the advantageous allele.
True or False:
Natural selection acts on individuals but results in evolutionary change in populations.
True
Individuals survive or reproduce differently, but allele frequencies change in populations.
What term describes the change in allele frequencies within a population over time due to differential reproductive success?
Evolution
Evolution occurs through processes such as natural selection.
What type of selection occurs when one extreme phenotype is favoured and the population mean shifts?
Directional selection
This type of selection drives traits in a particular direction.
What example commonly demonstrates directional selection caused by human activity in medicine?
Antibiotic resistance in bacteria
Resistant bacteria survive treatment and reproduce.
True or False:
Antibiotic resistance occurs because bacteria intentionally mutate to survive antibiotics.
False
Mutations occur randomly before, or during exposure to antibiotics.
What type of selection favours individuals with intermediate phenotypes and reduces extremes?
Stabilising selection
This type of selection maintains the status quo for a trait.
Which human trait is commonly used as an example of stabilising selection?
Birth weight
Very low or very high birth weights have higher mortality.
Fill in the blank:
Adaptations that involve body structures, such as limb shape, are called ______ adaptations.
anatomical
Adaptations can also be physiological or behavioural.
What type of adaptation involves internal processes such as enzyme activity or metabolism?
Physiological
Physiological traits improve function under certain conditions.
What type of adaptation involves the way an organism acts or responds to its environment?
Behavioural
Examples include migration or mating displays.
True or False:
Natural selection contributes to the diversity of living organisms.
True
Different environments favour different adaptations.
Why can bacterial populations evolve antibiotic resistance very rapidly?
Large population size and rapid reproduction
Large numbers increase mutation chances and selection acts quickly.
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3.1.1 Monomers & Polymers9
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3.1.2 Carbohydrates22
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3.1.3 Lipids17
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3.1.4 Proteins39
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3.1.5 Nucleic Acids32
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3.1.6 ATP11
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3.1.7 Water11
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3.1.8 Inorganic ions8
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3.2.1 Cell structure52
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3.2.2 Cell division20
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3.2.3 Transport across cell membranes20
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3.2.4 Cell recognition & the immune system36
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3.3.1 Surface area to volume ratio13
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3.3.2 Gas exchange24
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3.3.3 Digestion & absorption16
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3.3.4 Mass transport39
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3.4.1 DNA, genes & chromosomes13
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3.4.2 DNA & protein synthesis14
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3.4.3 Genetic diversity & meiosis14
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3.4.4 Genetic diversity & adaptation20
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3.4.5 Species & taxonomy20
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3.4.6 Biodiversity within a community12
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3.4.7 Investigating diversity12
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3.5.1 Photosynthesis23
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3.5.2 Respiration17
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3.5.3 Energy & ecosystems20
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3.5.4 Nutrient cycles15
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3.6.1 Stimuli & Response62
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3.6.2 Nervous coordination53
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3.6.3 Skeletal muscles14
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3.6.4 Homeostasis57
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3.7.1 Inheritance12
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3.7.2 Populations15
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3.7.3 Evolution may lead to speciation22
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3.7.4 Populations in ecosystems24
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3.8.1 Gene Mutations and Protein Structure14
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3.8.2 Control of Gene Expression44
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3.8.3 Applications of Genome Projects10
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3.8.4 Gene Technologies and Their Applications46
