Exam 1 BSC1005

elements of a good scientific study include:

Sample size, Control groups, Placebo effects, Randomization

Sample size

the number of times a measurement is replicated in data collection

Control groups

Groups of participants in a research experiment who do not receive the experimental treatment or intervention.

Placebo effects

The fact that subjects' expectations can lead them to experience some change even though they receive an empty, fake, or ineffectual treatment.

Randomization

a process of randomly assigning subjects to different treatment groups

observational studies

Researchers carefully and systematically observe and record behavior without interfering with behavior.

Randomized control studies

a study in which participants are allocated at random to receive one of several interventions, and one of these interventions is the standard of comparison or control

Bias

a prejudice in favor of something that is usually subconscious.

Pros and Cons of Randomized Controls

Pro: Very good detection of causation and reproducibility

Con: For health studies, the populations may not be like you.

Pros and Cons of Observational Studies

Pro: Big sample sizes are more likely to include people like you.

Con: Self selection and complex analysis make data less reliable

Confirmation bias

where one is more convinced by datathat supports preconceived notions, is likely one of themore prevalent types of bias in science.

Opinions

a belief or judgment that rests on grounds of insufficient fact for completed certainty

Facts

something that actually exists and can be proven true

Hypothesis

A testable prediction, often implied by a theory

Theory

A hypothesis that has been tested with a significant amount of data

Hypothesis Vs. Theory

a suggested explanation for an observable phenomenon, or a reasoned prediction of a possible causal correlation among multiple phenomena VS. a tested, well-substantiated, unifying explanation for a set of verified, proven factors.

When the Earth Cooled

approximately 4.5 billion years ago

When Life Arose on Earth

between 4.3 and 3.5 billion years ago

Conditions of Early Earth

There was liquid water, a lot of UV light, no oxygen, a lot of asteroid strikes, no organic molecules, a lot of lightning strikes, and a lots of other gases (methane,hydrogen sulfide, ammonia, carbondioxide, sulfur dioxide)

Life originated in 4 overlapping stages:

1. Nucleotides and amino acids produced prior to the existence of cells

2. Polymerization into larger molecules

3. Polymers became enclosed in membranes, forming protocells.

4. Origin of self-replicating molecules.

Reducing atmosphere hypothesis

Miller and Urey. 1950s. scientists proposed that the atmosphere on early Earth was rich in water vapor, hydrogen gas, methane, and ammonia. along with a lack of oxygen, produce a reducing atmosphere because methane and ammonia readily give up electrons to other molecules, thereby reducing them.

Extraterrestrial hypothesis

From floating space rocks and debris, Carbonaceous chondrite meteorites can contain a lot of organic material

Deep-sea vent hypothesis

Biologically important molecules may have been formed in the temperature gradient between extremely hot vent water and cold ocean water; Also supported by experiments

Polymers

A large compound formed from combinations of many monomers

Protocells

aggregate of pre-biotically produced molecules that acquired a boundary (e.g. lipid bilayer) that allowed it to maintain a distinct internal environment

Why RNA was the most likely candidate for the beginnings of early life

RNA likely was first (RNA world hypothesis)

○ RNA can store genetic information

○ And can replicate

○ And can do chemistry (which DNA can't)

Stromatolites

Large fossilized mounds of cyanobacteria; played a key role in the generation of an oxygenic atmosphere

Effects of The Great Oxygen Event (GOE)

Geological evidence shows O2 levels in oceans rose around 2 Gyr•

• Oxygen gets first bound in minerals, then saturated in the ocean, then allowed to accumulate in the atmosphere

• Resulted in a number of major changes to life on Earth

• Greatly expanded cycling of major elements

• Resulted in the formation of an ozone layer

• Encouraged evolution

• Allowed for endosymbiosis and "higher" life

Evolution

Heritable change in one or more characteristics of a population or species from one generation to the next

Natural Selection

The idea that the traits of the organisms that are best at surviving and reproducing will the be the ones that are most present in the next generation

Example of Natural Selection

EX. birds with adaptations (beak size/shape) that allow them to specialize in eating different foods

Natural selection leads to _______________

adaptations

Adaptations

changes in the traits of an organism that allow it to exploit its environment

Components of Natural Selection

Variation, Inheritance, Varying degrees of reproductive success

What is Linnean taxonomy and why is it useful?

Linnean taxonomy is a hierarchical system for classifying organisms based on shared characteristics, which helps in organizing biological diversity and understanding evolutionary relationships.

How can comparing the taxonomies of organisms provide insights into their relatedness?

Comparing taxonomies allows scientists to identify common ancestors and evolutionary pathways, revealing how different species are related.

What are the different kinds of biological symmetry?

The main types of biological symmetry include bilateral symmetry, radial symmetry, and asymmetry, which describe how organisms are structured.

What are the major classes of organisms and their key features?

Major classes include mammals, birds, reptiles, amphibians, and fish, each with distinct features such as body temperature regulation, reproduction methods, and habitat adaptations.

How do the features of major groups of organisms contribute to their role in the environment?

Features like mobility, feeding habits, and reproductive strategies influence how organisms interact with their ecosystems and contribute to ecological balance.

Why is metamorphosis important for the evolutionary success of arthropods?

Metamorphosis allows arthropods to exploit different ecological niches at various life stages, enhancing survival and reproductive success.

What are the functions of the nervous system and the endocrine system?

The nervous system coordinates rapid responses to stimuli, while the endocrine system regulates longer-term processes through hormone release.

Differentiate between the Central and Peripheral nervous systems.

The Central nervous system consists of the brain and spinal cord, while the Peripheral nervous system includes all other neural elements outside the CNS.

What is the difference between the Somatic and Autonomic nervous systems?

The Somatic nervous system controls voluntary movements, while the Autonomic nervous system regulates involuntary functions.

Differentiate between the Sympathetic and Parasympathetic nervous systems.

The Sympathetic nervous system prepares the body for 'fight or flight' responses, while the Parasympathetic nervous system promotes 'rest and digest' activities.

What is the role of blood in the body and what are the three types of blood vessels?

Blood transports oxygen, nutrients, and waste; the three types of blood vessels are arteries (carry blood away from the heart), veins (carry blood to the heart), and capillaries (exchange materials with tissues).

What is the purpose of the respiratory system and why is CO2 removal important?

The respiratory system facilitates gas exchange, supplying oxygen to the body and removing carbon dioxide, which is crucial for maintaining pH balance and preventing toxicity.

Why and where do we produce urine?

Urine is produced in the kidneys to remove waste products from the blood and regulate water and electrolyte balance.

Describe the three steps of urine production.

The three steps are filtration (removing waste from blood), reabsorption (recovering essential substances), and secretion (adding additional wastes).

Why do we need to digest our food?

Digestion breaks down food into smaller molecules that can be absorbed and utilized by the body for energy, growth, and repair.

What is the role of surface area for nutrient absorption in the small intestine?

Increased surface area enhances nutrient absorption; it is increased by structures like villi and microvilli.

What is a pathogen and an opportunistic pathogen?

A pathogen is a microorganism that causes disease, while an opportunistic pathogen takes advantage of weakened immune systems to cause infections.

Why is selective toxicity important for antibiotics?

Selective toxicity ensures that antibiotics can kill or inhibit bacteria without harming human cells.

What are the targets of antibiotics?

Antibiotics target specific bacterial structures or functions, such as cell wall synthesis, protein synthesis, or DNA replication.

How can a pathogen be resistant to an antibiotic?

Resistance can occur through mutations, gene transfer, or by acquiring mechanisms to evade the antibiotic's effects.

What is Horizontal Gene Transfer and how does it occur?

Horizontal Gene Transfer is the transfer of genetic material between organisms in a manner other than traditional reproduction, occurring via transformation, transduction, or conjugation.

Why is antibiotic resistance a problem and what can we do about it?

Antibiotic resistance leads to treatment failures and increased healthcare costs; strategies to combat it include responsible antibiotic use, infection control, and research into new treatments.

Compare and contrast specific and non-specific defenses in the immune system.

Specific defenses target specific pathogens and involve adaptive immunity, while non-specific defenses provide general protection against a wide range of pathogens.

What are the key players in specific and non-specific immune defenses?

Key players in specific defenses include lymphocytes (B cells and T cells), while non-specific defenses involve barriers (skin, mucous membranes) and phagocytes.

What are the roles of memory cells, plasma cells, antigen presenting cells (APC), helper T cells, cytotoxic T cells, and regulatory T cells?

Memory cells provide long-term immunity, plasma cells produce antibodies, APCs present antigens to T cells, helper T cells activate other immune cells, cytotoxic T cells kill infected cells, and regulatory T cells modulate immune responses.

What is an antibody and how does it work?

An antibody is a protein produced by plasma cells that binds to specific antigens, neutralizing pathogens or marking them for destruction.

What is the role of the lymphatic system in the immune response?

The lymphatic system transports lymph, filters pathogens through lymph nodes, and facilitates the activation of immune cells.

What disorders are associated with an immune response that is too strong or too weak?

Too strong an immune response can lead to allergies or autoimmune diseases, while a weak response can result in increased susceptibility to infections.