Human bio exam semester 1

Marsh king

What surrounds the cell and forms the outer boundary?

Cell membrane

The ________ is the site of protein synthesis.

Ribosome

The ________ modifies proteins and packages them for secretion.

Golgi body

The ________ contains DNA information and controls the structure and function of the cell.

Nucleus

The ________ is the jelly-like fluid in which organelles are suspended.

Cytoplasm

Define cytosol.

The liquid part of the cytoplasm, composed of 75–90% water and dissolved substances.

Define lysosome.

An organelle that contains digestive enzymes to break down waste or damaged organelles.

Define mitochondria.

Double-membraned organelle where cellular respiration occurs; produces ATP and energy for the cell.

Define endoplasmic reticulum.

A network of membranes providing a surface for chemical reactions and transport within the cell.

Define nucleolus.

A structure found in the nucleus, responsible for transcription and ribosome production.

What is the function of the Golgi apparatus?

It modifies proteins and packages them for secretion.

Why are mitochondria called the "powerhouse of the cell"?

Because they produce ATP during cellular respiration.

What are inclusions in a cell?

Chemical substances stored in the cytoplasm, such as pigments or droplets.

What is the cytoskeleton made of?

Microtubules and microfilaments that give shape and assist movement in the cell.

Which organelle would be most active in a pancreatic cell that secretes digestive enzymes?

Rough endoplasmic reticulum and Golgi body.

Which organelle would be least present in a red blood cell?

Nucleus (mature red blood cells have no nucleus).

Why do muscle cells have many mitochondria?

They require lots of energy (ATP) for contraction.

Which cell structure would be affected if a cell could not maintain its shape?

Cytoskeleton

Which organelle would accumulate waste if lysosomes were damaged?

Cytoplasm (damaged lysosomes fail to break down waste)

Diffusion is the movement of particles from areas of ______ concentration to areas of ______ concentration.

High, low

Osmosis is the diffusion of ______ across a semi-permeable membrane.

Water

Carrier proteins are ______ to specific molecules.

Specific

The form of transport that requires ATP is called ______.

Active transport

The cell membrane is described by the ______ model.

Fluid mosaic

Define osmosis.

The passive movement of water through a semi-permeable membrane from an area of high water concentration to an area of lower water concentration.

Define facilitated diffusion.

The passive transport of substances across the cell membrane using carrier or channel proteins.

Define vesicular transport.

An active process in which materials move into or out of a cell enclosed in membrane-bound vesicles.

Define active transport.

The movement of substances against a concentration gradient (from low to high), using energy (ATP).

Define endocytosis.

A process in which the cell membrane wraps around material and engulfs it into the cell.

What are the two main types of transport across the cell membrane?

Passive and active transport

How does glucose enter a cell?

Through facilitated diffusion using a glucose-specific carrier protein

Why can oxygen diffuse through the cell membrane easily?

It is a small, nonpolar molecule that can pass through the phospholipid bilayer

What is the role of channel proteins?

To provide a central pore through which ions, water, and other small molecules can pass

Why is the fluid mosaic model called “fluid”?

Because the molecules within the membrane are constantly moving

Why do cells need a high surface area to volume ratio?

To efficiently exchange materials (like oxygen and nutrients) across the cell membrane. Also allows for more contact points with villi to increase absorption.

If a red blood cell is placed in a hypertonic solution, what happens?

Water leaves the cell, and the cell shrinks

Why can only certain cells perform endocytosis?

Because only specialised cells have the receptors and machinery to engulf specific substances

In facilitated diffusion, what happens when all carrier proteins are occupied?

The rate of diffusion reaches a maximum and cannot increase further

Why do kidneys use active transport for certain ions?

To reabsorb essential ions against their concentration gradient

The outer layer of the skin is made of ______ tissue.

Epithelial

______ tissue provides support and holds all body parts together.

Connective

______ muscle is involuntary and found in the digestive tract.

Smooth

Nerve tissue contains specialised cells called ______.

Neurons

______ muscle is striated (Striped) and under voluntary control.

Skeletal

Define epithelial tissue.

Tissue that covers and lines surfaces of the body, including skin and organ linings.

Define connective tissue.

Tissue that supports, binds, or separates other tissues and organs. Includes bone, blood, and fat.

Define muscular tissue.

Tissue that contracts to produce movement; includes skeletal, cardiac, and smooth muscle.

Define nervous tissue.

Tissue made of neurons that transmit electrical impulses.

Define stratified squamous epithelium.

A type of epithelial tissue that protects against abrasion; found in skin, mouth, and vagna

Where is simple cuboidal epithelium found?

In kidney tubules and glands

What is the function of cardiac muscle?

To pump blood throughout the body by contracting involuntarily

How does skeletal muscle differ from smooth muscle?

Skeletal is voluntary and striated; smooth is involuntary and non-striated (non striped)

Which tissue type forms tendons and ligaments?

Connective tissue

Which type of muscle is only found in the heart?

Cardiac muscle

Why is simple squamous epithelium found in the lungs?

Its thin structure allows efficient gas exchange (one cell thick)

Why are red blood cells able to move easily through capillaries lined with simple squamous epithelium?

Because the thin barrier allows smooth, quick diffusion

If a muscle is damaged and does not regenerate quickly, what type is it likely to be?

Cardiac muscle

Why do epithelial tissues have a high rate of mitosis?

To replace cells lost from constant friction or exposure

Enzymes are biological ______ that speed up chemical reactions.

Catalysts

The molecule an enzyme acts on is called a ______.

Substrate

The part of the enzyme that binds to the substrate is called the ______.

Active site

Enzymes work best at an optimal ______, ______ and_____.

Temperature, pH and concentration

A ______ inhibitor blocks the active site of the enzyme.

Competitive

Define enzyme.

A protein that speeds up chemical reactions without being consumed in the process.

Define metabolism.

The sum of all chemical reactions occurring in the body.

Define catabolism.

Metabolic reactions that break large molecules into smaller ones, releasing energy.

Define anabolism.

Metabolic reactions that build large molecules from smaller ones, requiring energy.

Define coenzyme.

A non-protein molecule that assists enzymes in catalyzing a reaction.

What is the lock and key model?

An analogy that describes how enzymes are specific to the shape of their substrate.

Lock = substrate
Key = enzyme

What happens to enzymes at high temperatures?

They denature, losing their shape and function, breaking the active site.

What is the effect of increasing substrate concentration on enzyme activity?

It increases the rate of reaction until the enzymes are saturated.

What are enzyme inhibitors used for in medicine?

To block enzyme activity, such as antibiotics targeting bacterial enzymes

Why does enzyme activity decrease at low temperatures?

Because molecular motion slows down, reducing collisions between enzymes and substrates, leading to less reactions occuring.

Why does trypsin function best at 37°C?

Because it is a human enzyme, and 37°C is the body's optimal temperature.

How does pH affect enzyme function?

Each enzyme has an optimal pH, and deviations can change the shape of the active site.

Cellular respiration is a ______ process that provides energy for the cell.

Catabolic

The main source of energy in the body is ______.

Glucose

The molecule that stores energy for cell use is ______.

ATP (Adenosine Triphosphate)

Anaerobic respiration occurs in the absence of ______.

Oxygen

The waste product of anaerobic respiration in humans is ______.

Lactic acid

Define cellular respiration.

A series of chemical reactions that convert glucose and oxygen into carbon dioxide, water, and ATP.

Define ATP.

A molecule that stores and provides energy for cellular processes.

Define anaerobic respiration.

The breakdown of glucose without oxygen, resulting in less ATP and lactic acid.

Define aerobic respiration.

Cellular respiration that requires oxygen and produces up to 38 ATP per glucose molecule.

Define oxygen debt

The extra oxygen required after exercise to convert lactic acid back into glucose.

What is the balanced equation for cellular respiration?

Glucose + Oxygen → Carbon dioxide + Water + Energy (ATP)

Where does aerobic respiration occur?

In the mitochondria

Where does anaerobic respiration occur?

In the cytoplasm

How is ATP formed?

By adding a phosphate group to ADP using energy from respiration

What are the three stages of aerobic respiration?

Glycolysis, Krebs cycle (Citric acid cycle), and Electron Transport Chain

Why do muscle cells rely on anaerobic respiration during intense exercise?

Because oxygen delivery can't keep up with demand, so anaerobic respiration provides quick energy

What happens to lactic acid after exercise?

It is taken to the liver and converted back into glucose

Why is more heat than ATP produced during respiration?

Because 60% of the energy released is lost as heat to maintain body temperature

If mitochondria were removed from a cell, what would happen to ATP production?

Aerobic ATP production would stop, and the cell would rely on inefficient anaerobic respiration

How is energy stored in ATP?

In the high-energy bond between the second and third phosphate groups

The liquid part of blood is called ______.

Plasma

The most abundant cells in blood are ______.

Erythrocytes (Red Blood Cells)

White blood cells are known as ______.

Leucocytes

Blood vessels that carry blood away from the heart are called ______.

Arteries

The main function of ______ is to prevent blood loss by clotting.

Platelets