biology exam 1, sem 1

What is the basic unit of life in all living organisms?

the cell

Name three characteristics that distinguish living things from non-living things.

Growth, reproduction, and response to stimuli.

What is the difference between unicellular and multicellular organisms?

Unicellular organisms are made up of one cell, while multicellular organisms consist of many specialized cells.

Name two major types of cells and a key difference between them.

Prokaryotes (no nucleus) and eukaryotes (have a nucleus).

What is one structure found in prokaryotic cells but not in eukaryotic cells?

cell wall

List three organelles found in eukaryotic cells and their functions.

Nucleus: stores genetic material, Mitochondria: produces energy (ATP), Ribosomes: synthesizes proteins.

What common features do prokaryotes and eukaryotes share?

Both have a cell membrane, cytoplasm, and ribosomes.

why do cells divide

for growth, repair, and reproduction

How do prokaryotic cells divide?

By binary fission.

How do eukaryotic cells divide?

By mitosis.

Briefly describe the binary fission process.

The DNA replicates, the cell elongates, and the cell splits into two identical daughter cells.

What happens during mitosis?

The nucleus divides to produce two identical nuclei, followed by cytoplasm division.

How can uncontrolled cell division lead to cancer?

It causes abnormal growth and spread of cells forming tumors.

Name one similarity and one difference between binary fission and mitosis.

Similarity: Both produce genetically identical cells. Difference: Binary fission occurs in prokaryotes; mitosis in eukaryotes.

What is the main function of the cell membrane?

To control the movement of substances in and out of the cell.

Name two key components of the cell membrane.

Phospholipid bilayer and proteins.

What does it mean that the cell membrane is semi-permeable?

It allows some substances to pass through while blocking others.

How does the cell membrane regulate material exchange?

By selective transport mechanisms like diffusion, osmosis, and active transport.

What is diffusion?

Movement of molecules from high to low concentration, requiring no energy making it passive transport

What is osmosis?

Diffusion of water across a semi-permeable membrane.

What is the main difference between passive and active transport?

Passive transport requires no energy and moves substances down the concentration gradient; active transport requires energy and moves substances against the gradient.

Why is surface area to volume ratio important for cells?

A high ratio allows efficient exchange of materials.

What are endocytosis and exocytosis?

Endocytosis brings substances into the cell; exocytosis removes substances from the cell.

What does it mean when cells are specialized?

Cells have a specific structure to perform particular functions.

Where is the information needed for protein synthesis stored?

In genes, segments of DNA.

What are the two main stages of protein synthesis?

Transcription and translation.

Are all cells in a multicellular organism genetically identical?

Yes, they have the same genome.

What causes cells to differentiate?

Differential gene expression (some genes are switched on/off).

How is gene expression regulated?

Through mechanisms that switch genes on or off during development and after birth.

How can environmental factors affect gene expression?

They can alter gene expression and change an organism’s phenotype.

What is the hierarchy of biological organization in animals?

Cells → tissues → organs → organ systems.

How is tissue and organ structure related to function?

Their structure supports their specific functions.

Are organ systems independent?

No, they are interdependent.

How can lifestyle choices affect organ systems?

They impact their function and overall health.

Why do multicellular organisms need specialised exchange surfaces?

To efficiently exchange materials due to their large size.

What characteristics make exchange surfaces effective?

Thin, moist, and large surface area.

How do lungs or gills facilitate gas exchange?

By diffusion of gases across moist, thin membranes.

How do respiratory and circulatory systems work together?

Respiratory system exchanges gases; circulatory transports them.

Name two respiratory diseases that affect lung function.

Asthma and chronic obstructive pulmonary disease (COPD).

What are the four main processes in animal nutrition?

Ingestion, digestion, absorption, egestion.

What are mechanical and chemical digestion?

Mechanical: physical breakdown; chemical: breakdown by enzymes.

Name two parts of the digestive system.

Alimentary canal and digestive glands.

What is the function of villi?

To increase surface area for absorption.

Where are most nutrients absorbed?

In the ileum through villi.

How are minerals and water absorbed?

Through the walls of the colon.

What transport processes are involved in absorption?

Osmosis, diffusion, active transport, endocytosis.

What is egestion?

Removal of non-digestible waste as faeces.

What type of waste is removed by the excretory system?

Nitrogen-containing metabolic waste like urea.

What is a nephron?

The functional unit of the kidney responsible for filtration and reabsorption.

Name the parts of a nephron

Bowman's capsule, glomerulus, tubule.

How do kidneys maintain blood composition?

By filtering wastes and selectively reabsorbing useful substances.

How can severe kidney disease be treated?

By dialysis or kidney transplant.

What are the two types of circulatory systems?

Open and closed circulatory systems.

How are arteries, veins, and capillaries structured to suit their functions?

Arteries: thick walls for high pressure; veins: valves to prevent backflow; capillaries: thin walls for exchange.

What is double circulation?

Blood flows twice through the heart per circuit in mammals.

How many chambers does the human heart have?

Four chambers.

What causes the heartbeat?

Contractions of cardiac muscle and valve movements.

What is tissue fluid?

Fluid that bathes cells, formed from blood plasma.

Where does exchange of materials occur?

Between cells and plasma in capillaries.

How is the lymphatic system connected to the circulatory system?

It drains excess tissue fluid and returns it to the bloodstream.

What drives lymph flow?

Skeletal muscle contractions.

What exchange occurs in lymph capillaries?

Exchange between cells and lymph fluid.

Define a cell.

A cell is the smallest structural and functional unit of life.

What is a unicellular organism?

A unicellular organism consists of only one cell that performs all life processes.

What is a multicellular organism?

A multicellular organism is made up of many specialised cells working together.

Define prokaryote.

A prokaryote is a unicellular organism that lacks a membrane-bound nucleus and organelles.

Define eukaryote.

A eukaryote is an organism whose cells contain a nucleus and membrane-bound organelles.

What is binary fission?

Binary fission is a type of asexual reproduction in prokaryotes where the cell splits into two identical cells.

What is mitosis?

Mitosis is a type of cell division in eukaryotes that produces two genetically identical daughter cells.

Define cancer.

Cancer is uncontrolled cell division that can lead to tumour formation.

What is the cell membrane?

The cell membrane is a semi-permeable barrier that controls the movement of substances in and out of the cell.

Define diffusion.

Diffusion is the passive movement of particles from a high concentration to a low concentration.

Define osmosis.

Osmosis is the passive movement of water across a semi-permeable membrane from high to low water concentration.

What is active transport?

Active transport is the movement of substances against the concentration gradient using energy (ATP).

What is endocytosis?

Endocytosis is the process by which cells engulf external materials by folding the membrane inward.

What is exocytosis?

Exocytosis is the process by which cells release substances by fusing vesicles with the membrane.

Define cell differentiation.

Cell differentiation is the process by which cells become specialised to perform specific functions.

Define gene.

A gene is a segment of DNA that codes for a specific protein.

What is gene expression?

Gene expression is the process by which information from a gene is used to synthesise a protein.

What is a genome?

A genome is the complete set of DNA, including all genes, in an organism.

Define tissue.

A tissue is a group of similar cells working together to perform a specific function.

What is an organ?

An organ is a group of different tissues working together to perform a particular function.

Define organ system.

An organ system is a group of organs that work together to carry out complex functions.

What is gas exchange?

Gas exchange is the diffusion of oxygen and carbon dioxide between the organism and the environment.

Define surface area to volume ratio (SA:V).

SA:V is the amount of surface area per unit volume of a cell or organism, affecting exchange efficiency.

What is digestion?

Digestion is the breakdown of food into smaller molecules that can be absorbed by the body.

What is absorption?

Absorption is the uptake of digested nutrients into the bloodstream or cells.

Define villi.

Villi are finger-like projections in the small intestine that increase surface area for absorption.

What is egestion?

Egestion is the removal of undigested waste from the body as faeces.

What is excretion?

Excretion is the removal of metabolic waste products from the body.

Define nephron

A nephron is the functional unit of the kidney that filters blood and forms urine.

What is circulation?

Circulation is the transport of blood and other materials throughout the body.

What is tissue fluid?

Tissue fluid is fluid that surrounds cells, formed from plasma that leaks out of capillaries.

Define double circulation.

Double circulation means blood passes through the heart twice in one full circuit of the body.

What is the lymphatic system?

The lymphatic system is a network of vessels that drains excess fluid from tissues and helps fight infection.

What is lymph?

Lymph is the fluid transported through the lymphatic system, formed from tissue fluid.

What is telophase

the final stage of mitosis in which two nuclei are formed

tissue

a group of similar cells that are organized into a specific structure, muscle cells organized to form a muscle

tissue fluid

the fluid that occurs in between cells in multicellular organisms

trachea

the tube which takes air from the back of the throat to the lungs . it branches to form the two bronchi, one to each lung.