Unit 1 Biology exam

What is the basic unit of life?

The cell

What does the cell theory state?

All living things are made up of cells, all cells come from existing cells, and the cell is the basic unit of life.

What are the two main groups of cells?

Prokaryotes and eukaryotes

What is a key characteristic of prokaryotic cells?

They have a simpler structure and lack a nucleus.

What is a key characteristic of eukaryotic cells?

They have a complex structure with a defined nucleus and membrane-bound organelles.

What is the size range of prokaryotic cells?

Approximately 1-4 micrometers

What is the size range of eukaryotic cells?

Approximately 10-100 micrometers

Why do cells need to be small or have a high surface area to volume ratio (SA:V)?

To efficiently exchange nutrients and waste with their surroundings.

What happens if a cell has a low SA:V ratio?

Nutrient exchange will be poor, leading to toxic waste buildup.

What adaptations can increase a cell's surface area?

Developing projections like villi or microvilli.

What is the function of ribosomes?

They are the site of protein synthesis.

What is the role of the rough endoplasmic reticulum?

It folds proteins and packages them into vesicles for transport.

What does the Golgi body do?

It modifies proteins and packages them into vesicles for transport to the plasma membrane.

What is the function of mitochondria?

They serve as the energy powerhouse of the cell.

What is the role of the plasma membrane?

It controls what enters and exits the cell and acts as a barrier between the internal and external environment.

What is meant by 'semi-permeable' in relation to the plasma membrane?

It selectively allows certain substances to pass while blocking others.

What types of molecules can easily pass through the plasma membrane?

Small uncharged molecules, lipid-soluble molecules, and small water-soluble molecules.

What types of molecules cannot pass through the plasma membrane?

Large polar molecules and ions.

What is the function of chloroplasts?

They are the site of photosynthesis in plant cells.

What is the large central vacuole's role in plant cells?

It stores water and helps maintain turgor pressure.

What is the difference between organic and inorganic compounds?

Organic compounds are complex and contain hydrocarbon groups, while inorganic compounds are simpler and do not.

What are the four kingdoms of eukaryotes?

Protista, plants, fungi, and animals.

What is the significance of the endosymbiotic theory?

It suggests that chloroplasts and mitochondria originated from engulfed prokaryotic cells.

What is the role of the smooth endoplasmic reticulum?

It is the site of lipid synthesis.

How do substances get transported across the plasma membrane?

Based on their physical and chemical properties.

What is biogenesis?

The principle that all cells come from existing cells.

What is the structure of the plasma membrane?

It consists of a phospholipid bilayer with hydrophilic heads and hydrophobic tails.

What is the difference between polar and non-polar molecules?

Polar molecules have a slight positive and negative charge, while non-polar molecules do not.

What is passive transport?

Movement of molecules from high to low concentration without the need for ATP.

What are examples of passive transport?

Osmosis, diffusion, and facilitated diffusion.

What is the fluid mosaic model?

A model that describes the cell membrane as allowing components to move freely within the bilayer.

What is diffusion?

The net movement of a substance from high concentration to low concentration until equilibrium is reached.

How does temperature affect the rate of diffusion?

Higher temperatures increase kinetic energy, which speeds up the rate of diffusion.

What is simple diffusion?

The process by which hydrophobic molecules pass through the hydrophobic tail of the membrane.

What is facilitated diffusion?

The process by which hydrophilic molecules pass through the membrane with the help of protein channels.

What is active transport?

Movement of substances from low to high concentration that requires ATP and carrier proteins.

What are the two types of bulk transport?

Endocytosis and exocytosis.

What happens during endocytosis?

Material is taken into the cell as the cell membrane folds and creates vesicles.

What is the difference between pinocytosis and phagocytosis?

Pinocytosis involves moving fluids with small particles into the cell, while phagocytosis involves bringing in larger particles.

What is exocytosis?

The process of releasing content in bulk from the cell by vesicles fusing with the plasma membrane.

What is osmosis?

The movement of water molecules from high to low concentration across a semipermeable membrane without energy.

What is a hypertonic solution?

A solution where the external environment has a low water concentration, causing cells to shrink.

What is a hypotonic solution?

A solution where the external environment has a high water concentration, causing cells to swell.

What is an isotonic solution?

A solution where the internal and external environments have reached equilibrium, resulting in no net movement of water.

What is binary fission?

A method of asexual reproduction in prokaryotes and some eukaryotes where a cell duplicates and divides into two daughter cells.

What are the major phases of the cell cycle?

Interphase, mitosis, and cytokinesis.

What occurs during the G1 phase of the cell cycle?

The cell grows, synthesizes organelles, and gains ATP.

What is checked during the G1 checkpoint?

DNA replication and cell size.

What happens during the S phase of the cell cycle?

DNA replication occurs.

What is the role of the G2 checkpoint?

It checks for DNA damage, nutrient availability, and growth before mitosis.

What happens during early prophase?

DNA coils, centrioles appear and move to opposite poles, and the nuclear membrane begins to break down.

What occurs during metaphase?

Spindle fibers line up chromosomes vertically and chromosomes duplicate.

What is the outcome of anaphase?

Spindle fibers shorten, pulling apart chromosomes to opposite poles.

What happens during telophase?

Chromosomes reach the poles, DNA uncoils, and two nuclear membranes form in preparation for cytokinesis.

What is cytokinesis?

The process of splitting a cell into two daughter cells.

Define apoptosis.

Programmed cell death that can occur due to old, broken, or unnecessary cells.

What are the two types of apoptosis?

Intrinsic pathway and extrinsic pathway.

What is the intrinsic pathway of apoptosis?

A pathway where programmed cell death is initiated inside the cell, involving mitochondria.

What triggers the intrinsic pathway?

Internal damage detected in the cell cycle leads to the release of cytochrome C from mitochondria.

What is the role of caspases in apoptosis?

Caspases are enzymes that break down nuclear proteins, DNA, and the plasma membrane during apoptosis.

What is the extrinsic pathway of apoptosis?

A pathway where programmed cell death is initiated by external signaling molecules binding to death receptors.

What happens to a cell during apoptosis?

The cell shrinks, blebs into apoptotic bodies, and is engulfed by macrophages.

What is necrosis?

Cell death that occurs when a damaged cell bursts open, causing inflammation and potentially infecting other cells.

What can result from malfunctions in apoptosis?

Cancer can result if apoptosis does not occur, while excessive apoptosis can lead to conditions like autoimmune diseases.

What are the checkpoints in the cell cycle?

G1 checkpoint (checks DNA damage), G2 checkpoint (checks DNA replication and cell size), M checkpoint (checks chromosome spindle attachment).

What are stem cells?

Undifferentiated cells that have the ability to differentiate into specialized cells.

What are the two types of stem cells?

Embryonic stem cells and adult stem cells.

What is the potency of stem cells?

The ability of stem cells to differentiate into specialized cells, categorized as totipotent, pluripotent, or multipotent.

What are totipotent stem cells?

Cells that can differentiate into any specialized cell, including the placenta, such as zygotes.

What are pluripotent stem cells?

Cells that can differentiate into any specialized cell but not the placenta, such as those from a blastocyst.

What are multipotent stem cells?

Cells that can differentiate into specialized cells but only within a certain group, such as adult stem cells.

What is the structure of a blastocyst?

It has three layers: mesoderm, endoderm, and ectoderm, with a hollow center containing the inner mass that can differentiate.

What are induced pluripotent stem cells (iPSCs)?

Pluripotent cells created by reverting differentiated cells back to an embryonic stage using chemical hormones.

What is transpiration in plants?

The process of water movement from roots to leaves, primarily through xylem.

What is the function of xylem?

Xylem is a one-way tissue that transports water and minerals from roots to leaves.

What is the function of phloem?

Phloem is a two-way tissue responsible for the translocation of glucose and sugars throughout the plant.

What factors affect the rate of photosynthesis?

Light intensity, wind speed, and temperature can all increase the rate of photosynthesis.

How does temperature affect photosynthesis?

As temperature increases, the rate of photosynthesis increases due to more energetic enzymes.

What happens to water in leaves during transpiration?

Water evaporates into water vapor, which can then exit through stomata.

What is the role of guard cells?

Guard cells swell to open stomata, allowing gas exchange and the release of oxygen.

What is the significance of apoptosis in health?

Apoptosis is crucial for removing damaged or unnecessary cells, maintaining tissue health.

What are the two types of vascular tissues in plants?

Xylem and Phloem

What is the primary function of xylem?

To transport water and minerals through a transpiration stream.

What is the structure of xylem?

Xylem is dead tissue that holds structure and contains lignin.

What is the primary function of phloem?

To transport sugars like glucose around the tree.

What is the process called that moves water from the roots to the leaves?

Transpiration pull

What happens to water when it reaches the leaves?

It warms up and turns into water vapor.

What triggers the stomata to open?

When guard cells swell due to water vapor.

How does temperature affect transpiration?

Increased temperature increases transpiration due to higher enzyme activity.

What effect does increased humidity have on transpiration?

Increased humidity decreases transpiration.

What are the inputs of the light-dependent reactions of photosynthesis?

H2O, ADP + Pi, NADP

What are the outputs of the light-dependent reactions of photosynthesis?

O2, ATP, NADPH

What are the inputs of the Calvin cycle?

NADPH, ATP, CO2

What is produced in the Calvin cycle?

C6H12O6 (glucose), NADP+, ADP + Pi

What is the main purpose of the human digestive system?

To break down food into its simplest molecules.

What are the main organs of the human digestive system?

Mouth, esophagus, small intestine, large intestine, rectum, anus.

What is the role of accessory organs in the digestive system?

They produce resources for digestion but do not physically participate.

What are the two types of digestion in the body?

Mechanical digestion and chemical digestion.

What is the function of the kidneys in the excretory system?

To produce urine and regulate osmosis.

What is the role of hormones in the endocrine system?

Signaling molecules that travel through the bloodstream to target cells.