IB Biology Topic A3.1.1 Variation Between Organisms as a Defining Feature of Life Revision Notes (SL/HL)

IB Biology Topic A3.1.1 Variation Between Organisms as a Defining Feature of Life Revision Notes (SL/HL) | RevisionDojo

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No Two Organisms Are Identical In All Their Traits

Definition

Variation

Variation refers to differences in traits among individuals within a population, encompassing physical characteristics, behaviors, and genetic sequences.

Variation can manifest as differences in:
1. Morphological traits: e.g., fur color in cats, height in plants.
2. Behavioral traits: e.g., bird mating displays, migration patterns.
3. Biochemical traits: e.g., enzyme variants, antibiotic resistance in bacteria.

Note

Even closely related organisms, such as siblings, exhibit variation because each inherits a unique combination of alleles during reproduction.

How Genetic and Environmental Factors Cause Variation

Genetic Causes

Every individual of a species has a unique combination of alleles, except in the case of identical twins or clones.
Genetic variation is introduced by:
1. Mutation: Permanent changes in DNA sequences create new alleles.
2. Meiosis: Processes such as crossing over (exchange of DNA between homologous chromosomes) and independent assortment of chromosomes create novel genetic combinations in gametes.
3. Fertilization: Random fusion of gametes during sexual reproduction ensures that each zygote is genetically unique.

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Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

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No Two Organisms Are Identical In All Their Traits

Definition

Variation

Variation refers to differences in traits among individuals within a population, encompassing physical characteristics, behaviors, and genetic sequences.

Variation can manifest as differences in:
1. Morphological traits: e.g., fur color in cats, height in plants.
2. Behavioral traits: e.g., bird mating displays, migration patterns.
3. Biochemical traits: e.g., enzyme variants, antibiotic resistance in bacteria.

Note

Even closely related organisms, such as siblings, exhibit variation because each inherits a unique combination of alleles during reproduction.

How Genetic and Environmental Factors Cause Variation

Genetic Causes

Every individual of a species has a unique combination of alleles, except in the case of identical twins or clones.
Genetic variation is introduced by:
1. Mutation: Permanent changes in DNA sequences create new alleles.
2. Meiosis: Processes such as crossing over (exchange of DNA between homologous chromosomes) and independent assortment of chromosomes create novel genetic combinations in gametes.
3. Fertilization: Random fusion of gametes during sexual reproduction ensures that each zygote is genetically unique.

Definition

Paywall

(on a website) an arrangement whereby access is restricted to users who have paid to subscribe to the site.

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Note

Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam quis nostrud exercitation.

Excepteur sint occaecat cupidatat non proident

Tip

Lorem ipsum dolor sit amet, consectetur adipiscing elit.
Sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.
Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris.
Duis aute irure dolor in reprehenderit in voluptate velit esse cillum.

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

IB Biology Topic A3.1.1: Variation Between Organisms as a Defining Feature of Life Notes

A - Unity and Diversity9 subtopics

B - Form and Function10 subtopics

C - Interaction and Interdependence9 subtopics

D - Continuity and Change12 subtopics

No Two Organisms Are Identical In All Their Traits

How Genetic and Environmental Factors Cause Variation

Genetic Causes

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account

No Two Organisms Are Identical In All Their Traits

How Genetic and Environmental Factors Cause Variation

Genetic Causes

anim nostrud sit dolore minim proident quis fugiat velit et eiusmod nulla quis nulla mollit dolor sunt culpa aliqua

Duis aute irure dolor in reprehenderit

Excepteur sint occaecat cupidatat non proident

Unlock the rest of this chapter with a free account