life sciences

Q: What are the four basic needs of all organisms?

Air (for respiration), Water (chemical reactions and transport), Shelter (protection and suitable environment), Nutrients (energy, growth, and repair).

Why do organisms need air?

To obtain oxygen for cellular respiration (or carbon dioxide for photosynthesis in plants).

Why do plants need nutrients such as phosphorus?

Nutrients help plants grow, build important molecules like DNA, develop strong roots, and carry out life processes.

8 characteristics of life?

Cells, Homeostasis, Energy use, Reproduction, Growth and development, Response to stimuli, Change over time (evolution), Traits passed to offspring (heredity).

Define the 8 characteristics of life

Cells—made of one or more cells. Homeostasis—maintain stable internal conditions. Energy use—obtain and use energy. Reproduction—produce offspring. Growth and development—increase in size and change over time. Response to stimuli—react to the environment. Change over time—populations evolve. Heredity—pass DNA to offspring.

What is homeostasis?

The ability to maintain a stable internal environment despite external changes.

what is the order of organization in multicellular organisms?

Cells → Tissues → Organs → Organ Systems → Organism

Cell

Basic unit of structure and function for all living things.

Tissue

A group of similar cells working together

Organ

A group of tissues working together, can be different kinds of tissues.

Organ system

Group of organs working together to perform a function. E.g. cardiovascular system

Organism

An individual animal, plant, or single celled life form.

Differences between prokaryotes and eukaryotes?

Prokaryotes: no nucleus or membrane-bound organelles, usually unicellular, smaller. Eukaryotes: have a nucleus and membrane-bound organelles, larger, can be unicellular or multicellular.

Difference between unicellular and multicellular?

Unicellular organisms consist of one cell that performs all life functions. Multicellular organisms consist of many specialized cells that work together.

How does the structure of a nerve cell relate to its function?

long extensions to send signals.

How does the structure of a red blood cell relate to its function?

Disc like shape to quickly transport oxygen through the body

How does the structure of the sperm cell relate to its function?

Long tail for swimming, head to enter egg and carry DNA

Why is the melanin gene turned off in the heart cell?

The heart is not exposed to sunlight, thus it does not need protection from sunlight, which is provided by melanin.

Stem cells

Cells that have not undergone cell differentiation and can become any cell in the body. Can be used to repair damaged organs and cure some diseases.

Difference between cell specialization and differentiation?

Cell differentiation is the process, specialization is the result.

What process is responsible for cell differentiation?

Gene expression: a process in which a gene is switched on or off, resulting in different proteins being made

prokaryotes

Simple, unicellular organisms that have no membrane bound organelles. All prokaryotes are bacteria.

Eukaryotes

Complex organisms that can be unicellular or multicellular. Contains organelles surrounded by membranes.

Unicellular organism

Can be prokaryotes or eukaryotes. Consists of only one cell that carries out all the functions required to maintain life. No cell specialization.

multicellular organism

Made of multiple cells that develop differently (differentiation), therefore having different appearances that suit their function.

Cell differentiation

the process where unspecialized stem cells develop into cells with distinct functions.

cell specialization

Cells are specialized to perform certain functions.

Neurons

Sends info from one part of the body to another.

Red blood cells

Carry oxygen through the body through blood vessels.

Sperm cells

Fertilizes egg cell

Gene expression

A process in which a gene is switched on or off, resulting in different proteins being made.

What is the equation for photosynthesis?

6CO2+6H2O+sunlight—>C6H12O6+6O2

What is the equation for cellular respiration?

C6H12O6+6O2—>6CO2+6H2O+ATP

One adaptation: Snake

Can unhinge jaw to swallow prey whole.

Adaptation: Kangaroo

Large ears to hear predators

Adaptation: Leopard

Teeth designed for meat eating

Adaptation; Monkey

Opposable thumbs for grabbing items

Adaptation: Elephant

Large tusks for defence

Spider

Can easily sense vibrations

Origin of Species hypothesis I

Aristotle believed all plants and animals had been placed on the Earth at its beginning and none have ever changed.

Law of use and disuse

The more often a body part is used, the more developed it will be.

Inheritance of acquired characteristics

The more developed or underdeveloped features are passed onto offspring

How was Lamarck’s theory proven wrong?

August Weissman cut off the tails of 50 generations of mice and there was no change in tail length

Darwin’s theory of evolution

Evolution happens become of natural selection.

4 Factors of evolution

Struggle for survival, inheritable variation, variation of fitness, time

Adaptation

A trait that helps an organism survive and reproduce in its environment. can be structure or behaviour

How can you tell if two animals are the same species after they produce offspring?

If the offspring are healthy and fertile (can reproduce), the parents are the same species. If the offspring are sterile (like a mule) or cannot survive, they are different species.

Convergent evolution

Convergent evolution occurs when unrelated species evolve similar adaptations because they live in similar environments and experience similar selective pressures. It produces analogous structures (same function, different origin).

Divergent evolution

Divergent evolution occurs when closely related species evolve different traits after becoming isolated and adapting to different environments.

Coevolution

Coevolution is when two species evolve in response to each other, with adaptations in one species driving adaptations in the other.

Analogous structures

Structures that have the same function but different evolutionary origins, such as the wings of birds and insects.

Evolution

• The change in inherited traits (allele frequencies) of a population over generations.

Speciation

• The formation of a new species when populations become reproductively isolated and genetically different.

3 ways mutation can occur

Chemicals, Radiation, DNA replication

What are the four factors that affect allele frequencies in a population?

1. Natural selection

2. Gene flow (movement of genes between populations)

3. Genetic drift (random changes in allele frequencies)

4. Mutation

How does inbreeding increase the chance of expressing a recessive deleterious allele?

Closely related individuals are more likely to carry the same harmful recessive allele, increasing the chance that offspring inherit two copies and express the trait.

How are artificial selection and natural selection similar and different?

Similar: Both change allele frequencies by selecting certain traits.

Different:

• Natural selection: Environment chooses.

• Artificial selection: Humans choose (selective breeding).

• Mutation

• Mutagen

• Gene pool

• Gene flow

• Genetic drift

• Bottleneck effect

• Founder effect

• Inbreeding

• Deleterious allele

• Artificial selection

• Sickle cell anemia

• Mutation: Change in DNA.

• Mutagen: Agent that causes mutations.

• Gene pool: All alleles in a population.

• Gene flow: Movement of alleles between populations.

• Genetic drift: Random change in allele frequencies.

• Bottleneck effect: Reduced population decreases genetic diversity.

• Founder effect: New population started by a few individuals.

• Inbreeding: Mating between close relatives.

• Deleterious allele: Harmful allele.

• Artificial selection: Humans breed organisms for desired traits.

• Sickle cell anemia: Genetic disorder caused by a mutation in hemoglobin; carrying one copy also provides some resistance to malaria.

What are the five types of evidence that support evolution?

Homologous structures, Vestigial structures, DNA evidence, Embryological development, fossils

What is the difference between homologous and analogous structures?

• Homologous structures: Same evolutionary origin, different functions (e.g., human arm and whale flipper).

• Analogous structures: Different evolutionary origins, same function (e.g., bird wing and insect wing).

If different animal embryos look similar in early development, what does this suggest?

It suggests they share a common ancestor. Similar embryological development is evidence of evolutionary relationships.

Why is the fossil record useful? What are its limitations?

Useful because it:

• Shows how organisms have changed over time.

• Provides evidence of extinct species and transitional forms.

• Helps determine when species lived.

Limitations:

• Fossils are rare because most organisms do not fossilize.

• The fossil record is incomplete, with many gaps.

• Older fossils may have been destroyed by erosion or geological activity.

Gradualism

• Evolution occurs slowly and continuously over long periods.

Punctuated equilibrium

• Long periods of little or no change are interrupted by short bursts of rapid evolution, often after environmental changes or isolation.

• Homologous structure

• Vestigial structure

• DNA evidence

• Embryological development

• Fossil record

• Gradualism

• Punctuated equilibrium

• Homologous structure: Same evolutionary origin, different functions.

• Vestigial structure: A reduced structure inherited from ancestors that has little or no current function.

• DNA evidence: Comparing DNA or protein sequences to determine evolutionary relationships.

• Embryological development: Comparing embryos of different species to identify common ancestry.

• Fossil record: Preserved remains or traces of organisms that show evolutionary change over time.

• Gradualism: Slow, continuous evolutionary change.

• Punctuated equilibrium: Long periods of little change interrupted by rapid evolution.