Notes, summaries, assignments, exams, and problems for Biology

Arthropod Characteristics

Arthropods are coelomate, segmented, invertebrate animals exhibiting bilateral symmetry. They possess an exoskeleton and jointed appendages. They were the earliest invertebrates to have jointed appendages.

Respiration Methods

1. Sensory Receptors

Sensory receptors are responsible for perceiving information, which they convert into a nerve impulse. The nerve impulse travels to the brain and produces feeling.

1.1. Types of Sensory Receptors

Sensory receptors can be classified according to the stimuli that they can receive, or by where they are located.

1.1.1. According to the Stimuli

• Photoreceptors: They detect light stimuli and are located in the eye.
• Mechanoreceptors: They are stimulated by mechanical changes such as pressure, contact, or sound waves.
• Chemoreceptors: They respond to chemical changes.
• Thermoreceptors: They detect temperature changes.

1.1.2. According to Their Location

• Internal receptors: They are located in the internal organs where they collect information

Muscle Fiber

Elongated cells that make up skeletal muscle tissue

Striation

Light and dark stripes in which skeletal muscle fibers are grouped

Fascicle

Dense bundles in which skeletal muscle fibers are grouped

Voluntary Muscle

Muscle that are consciously controlled

Involuntary Muscle

Smooth muscles that cannot be consciously controlled

Myofibril

Thread-like structures found in skeletal muscle fiber

Myosin

Thick filaments that make up myofibril

Actin

Thin filaments that make up myofibril

Z Line

Structure to which actin filaments are anchored

Sarcomere

The region from one Z line to the nerve

Tendon

Fibrous connective tissue that attaches muscles to bone

Flexor

Muscle that bends a joint

Extensor

Muscle that straightens a joint

Muscle Fatigue

Physiological inability of a

Lymphatic System: Components and Functions

The lymphatic system is composed of lymph, lymphatic vessels, lymphatic organs, lymphatic tissues, and lymph nodes.

Key Components of the Lymphatic System

Lymph

Lymph is a transparent liquid composed of lymphocytes and interstitial plasma that is formed when blood plasma is filtered as it travels to the tissues.

Lymphatic Vessels

Lymphatic vessels are closed at one end. Lymphatic capillaries are found in tissues, and they join into bigger conduits known as lymphatic veins that eventually connect with blood veins.

Lymphatic Organs and Tissues

Lymphatic organs and tissues perform several functions, such as producing and maturing lymphocytes and purifying blood. The most important lymphatic organs are the spleen... Continue reading "Human Body Systems: Lymphatic, Excretory, and Urinary Functions" »

Core Principles of Photosynthesis

The Light-Dependent Reactions

1. When oxygen is released during photosynthesis, what is it a direct by-product of?

   It is a direct by-product of splitting water molecules.

2. What is the role of pigment molecules in a light-harvesting complex?

   Within the thylakoid membranes, they absorb and transfer light energy to the reaction-center chlorophyll.

3. What is directly associated with photosystem I?

   It is directly associated with receiving electrons from the thylakoid membrane's electron transport chain.

4. How can one detect the lack of photosystem II in certain photosynthetic organisms?

   The most effective method is to test for the liberation of O2 in the presence of light, as photosystem II is responsible for splitting water to

Infectious Diseases: Causes, Symptoms & Prevention

Common Infectious Conditions

• CP (Common cold): virus - headache, loss of appetite. Keep hydrated.
• Influenza: virus - high fever, pains in back and muscles. Rest.
• Measles: virus - vomiting, diarrhea, sweating. MMR vaccine.
• Tuberculosis: bacteria - weight loss, fever. Antibiotics.
• Bubonic plague: Yersinia pestis (bacterium) - muscle cramps, chills.
• Cholera: bacterial infection - leg cramps, vomiting, diarrhea. Antibiotics.
• Tetanus: bacteria - stiffness. Vaccination or antitoxin.
• Malaria: protozoa - fever, muscle pain, diarrhoea. Medicines.
• Sleeping sickness: protozoa - fever, itchiness. Different medications.
• Athlete's foot: fungus - infection of the skin. Pharmacy creams.
• Ringworm: fungus - a red rash

Fundamental Knowledge Challenge

Earth Science & Geology

Formation of Smooth Stones

Which of these is the best explanation of how a smooth, round stone becomes smooth? It was in a stream for a long time.

Key Processes of the Water Cycle

Processes of the water cycle include: Evaporation, condensation, sublimation, and so on.

Formation of Water Droplets

The process by which water droplets form is: Condensation.

Astronomy & Physics

Defining Astronomical Bodies

Any astronomical body that revolves around a larger body is called a: Satellite.

Understanding Friction

Friction is the force that: Opposes motion between two surfaces.

Measuring Liquid Resistance to Flow

When scientists measure a liquid's resistance to flow, they are measuring its: Viscosity.

Biology

Transcription: From DNA to RNA

Steps of Transcription

Initiation

• Transcription begins when transcription factors bind to a specific nucleotide sequence of DNA known as the promoter region or the "TATAA box."
• These transcription factors signal RNA polymerase II to attach to the DNA at the promoter.

Elongation

• Once attached to the DNA, RNA polymerase synthesizes a single-stranded RNA molecule in a 5’ → 3’ direction.
• RNA nucleotides are added to the growing polymer, which are complementary to the DNA template.

Termination

• Eventually, RNA polymerase will reach a termination sequence in the DNA.
• This causes RNA polymerase to release the newly synthesized mRNA and to dislodge from the DNA.

Note: The template strand is also known as the antisense strand,

Meiosis and Genetic Variation

Question 58

Which of the following occurs in meiosis but not in mitosis?

B) synapsis of chromosomes

Question 59

Crossing over normally takes place during which of the following processes?

B) meiosis I

Question 60

Homologous pairs of chromosomes align opposite of each other at the equator of a cell during _____.

B) meiosis metaphase I

Question 61

When homologous chromosomes cross over, what occurs?

C) Corresponding segments of non-sister chromatids are exchanged.

DNA Structure and Replication

Question 62

Which of the following people conducted the experiments that demonstrated that DNA is the genetic material of bacteriophages?

B) Avery, Hershey and Chase

Question 63

One type of virus that infects bacteria is called a

A) phage.

Question