IB Biology HL Exam Review

Outline the cell theory.

Living organisms are composed of cells.

Cells are the smallest unit of life.

Cells come from pre-existing cells.

Discuss the evidence for the cell theory.

The nature of scientific theories could be introduced here: the accumulation of evidence that allows a hypothesis to become a theory; whether a theory should be abandoned when there is evidence that it does not offer a full explanation; and what evidence is needed for a theory to be adopted or rejected.

State that unicellular organisms carry out all the functions of life (Name the six functions).

Metabolism, response, homeostasis, growth, reproduction, and nutrition.

Compare the relative sizes of molecules, cell membrane thickness, viruses, bacteria, organelles, and cells using the appropriate SI unit.

Molecules: 1 nm

Thickness of membranes: 10 nm

Viruses: 100 nm

Bacteria: 1 um

Organelles: (up to) 10 um

Most cells: (up to) 100 um

Explain the importance of the surface area to volume ratio as a factor limiting cell size.

The rate of heat production/waste production/resource consumption of a cell is a function of its volume, whereas the rate of exchange of materials and energy (heat) is a function of its surface area.

State that multicellular organisms show emergent properties. [pen analogy]

Emergent properties arise from the interaction of component parts: the whole is greater than the sum of its parts.

How do multicellular organisms differentiate to carry out specialized functions?

By expressing some of their genes but not others.

What two abilities do stem cells have?

Stem cells retain the capacity to divide and have the ability to differentiate along different pathways.

Outline one therapeutic use of stem cells.

In 2005, stem cells were used to restore the insulation tissue of neurons in laboratory rats, resulting in subsequent improvements in their mobility.

How do prokaryotic cells divide?

Binary fission

Compare prokaryotic and eukaryotic cells.

Naked DNA vs. DNA associated with proteins

DNA in cytoplasm vs. DNA enclosed in a nuclear envelope

No mitochondria vs. mitochondria

70s vs. 80s ribosomes.

Eukaryotic cells have internal membranes that compartmentalize their functions.

Outline two roles of extracellular components.

The plant cell wall maintains cell shape, prevents excessive water uptake, and holds the whole plant up against the force of gravity.

Animal cells secrete glycoproteins that form the extracellular matrix. This functions in support, adhesion, and movement.

List the functions of membrane proteins.

Hormone binding sites, immobilized enzymes, cell adhesion, cell-to-cell communication, channels for passive transport, and pumps for active transport.

Define diffusion.

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

Define osmosis.

Osmosis is the passive movement of water molecules, across a partially permeable membrane, from a region of lower solute concentration to a region of higher solute concentration.

Explain passive transport across membranes by simple diffusion and facilitated diffusion.

Simple: just passing through

Facilitated: passive

Briefly explain a sodium-potassium pump.

3 Na out, 2 K in

What are tumors a result of?

Uncontrolled cell division

Outline interphase.

Interphase is an active period in the life of a cell when many metabolic reactions occur, including protein synthesis, DNA replication, and an increase in the number of mitochondria and/or chloroplasts.

Insulin

Beta cells of the pancreas; converts glucose to glucogen; released when blood sugar is high.

Glucagon

Alpha cells of the pancreas; converts glycogen to glucose; released when blood sugar is low.

Adrenaline

"Fight or flight" increases heart rate

Testosterone

Sperm production, male body development

FSH

Stimulates oocyte development

LH

Develops endometrium

Oestrogen

Stimulates ovulation (release of the egg)

Progesterone

Maintains endometrium

HCG

Maintains high levels of estrogen and progesterone in pregnancy

Oxytocin

Causes contraction of the uterus during childbirth

What are the two mechanics of ventilation?

Inspiration and Expiration

What happens during inspiration?

1. External intercostal muscles contract.

2. Diaphragm contracts (drops) and abdominal muscles relax.

3. Chest volume increases.

4. Pressure in lungs decreases

5. Air enters.

What happens during expiration?

1. Internal intercostal muscles contract. 2. Diaphragm relaxes (rises).

3. Abdominal muscles contract.

4. Chest volume decreases.

5. Pressure in lungs increases

6. Air is pushed out.

What are the four methods of membrane transport in nerves and synapses?

Active transport, simple diffusion, facilitated diffusion, and vesicle transport.

What is ventilation?

The movement of air in and out of the lungs.

What is gas exchange?

The exchange of oxygen and carbon dioxide at the alveoli.

What is the net yield of glycolysis?

2 ATP

What happens in oxidation?

Loss of electrons

Gain oxygen

Loss of hydrogen

What happens in reduction?

Gain electrons

Loss of oxygen

Gain hydrogen

Where does the Kreb's Cycle occur?

The matrix of the mitochondria

Where does link reaction occur?

The matrix of the mitochondria

Where does glycolysis occur?

The cytoplasm

What is decarboxylation?

Losing carbon as carbon dioxide

State two types of meristems found in plants.

Apical and lateral

In monocots, the leaves are arranged in multiples of what?

3

In dicots, the leaves are arranged in multiples of what?

4 or 5

How many cotyledons do monocots have?

One

How many cotyledons do dicots have?

Two

How is the vascular tissue arranged in monocots?

Random distribution

How is the vascular tissue arranged in dicots?

Arranged in rings

What veins do monocots have?

Parallel

What veins do dicots have?

Branched

Where is the apical meristem found in plants?

At the root stem or tip

Where is the lateral meristem found in plants?

Thickening layers of cambium.

What two things can terrestrial plants support themselves with?

Roots and stems.

Explain how roots absorb water and then transport it to the xylem, noting any special adaptations that help these processes to occur.

Mineral ions are diffused slowly towards the root, generating a small concentration gradient. Water and solutes are literally sucked up into the roots, which generates a gradient of hydrostatic pressure. The water is carried up the stem to the rest of the plant through the xylem vessel. Lignin rings are present periodically through the length of the stem for added support too.

Outline the role of the poem in the active translocation of biochemicals.

The movement of phloem sap requires energy. The food needs to be transported (translocated) for the plant to grow and reproduce, so it is called active translocation.

Describe the metabolic events of germination in a starchy seed.

1. Water is absorbed through the microphyle and activates cells

2. Synthesis of gibberelins (plant growth hormones)

3. Gibberelins cause synthesis of amylase

4. Amylase hydrolyses stored starch to maltose.

5. Maltose absorbed by plumule and radicle.

6. Further hydrolysis breaks maltose into glucose, which is used for respiration in the growing tissues.

State four factors that affect the rate of transpiration.

Light, wind, temperature, and humidity.

State four things needed to start germination.

Oxygen for respiration, ideal temperature, pH, and water.

What is the first identifiable product of carbon dioxide fixation in photosynthesis?

Triose phosphate (TP)

What substance is moved into the thylakoids of the chloroplast using energy derived from light?

Protons (H+)

What is needed in photosynthesis to convert carbon dioxide into organic molecules?

ATP and hydrogen from the splitting of water

How is the proton gradient generated in chloroplasts during photosynthesis?

Flow of electrons from carrier to carrier in the thylakoid membrane causes pumping of protons across the thylakoid membrane.

What would be the effect of increasing temperature on the rate of photosynthesis in a green plant?

It increases up to a point and then decreases.

What is the sequence of chemicals produced in the anaerobic respiration pathway?

Glucose—pyruvate—lactate

What is the "link reaction" in eukaryotic respiration?

Pyruvate joining with coenzyme A to produce carbon dioxide and NADH + H+

What are the most frequently occurring chemical elements in living things?

Carbon, hydrogen, nitrogen, and oxygen.

Job of the renal capsule

Ultrafiltration

Job of the Proximal convoluted tubule

Selective reabsorption

Job of the distal convoluted tubule

Secretion of toxins into urine

Job of the glomerulus

Delivers blood

Job of the Loop of Henle

Osmoregulation

Job of the Collecting duct

Delivers urine to pelvis

What is the functional unit of the kidney?

The nephron

What is excretion?

The removal from the body of waste products of metabolism.

What does the Urinary (Excretory) System do?

Filters blood and produces urine

What is the blood's filtration and balancing system?

The Kidney

Job of the medulla

Reabsorption of water

Job of the cortex

Ultrafiltration and selective reabsorption of blood contents

Job of the pelvis

Collecting ducts deliver urine to the pelvis to be passed on to the ureter

Job of the ureter

Carries urine to the bladder

Where does selective reabsorption occur?

The proximal convoluted tubule (of the nephron)

Selective reabsorption includes what three substances?

Glucose, water, and salts

What percentage of water is recovered after selective reabsorption?

65%-80% of water is recovered

What percentage of glucose and amino acids are recovered in selective reabsorption?

100% of glucose and amino acids are recovered.

What does facilitated diffusion carry into the blood?

Glucose and amino acids

What is osmoregulation?

The control of the water balance of the blood, tissue, or cytoplasm of a living organism

What does the Loop of Henle generate in the cells and fluid of the medulla?

A high concentration of solutes

Descending loop vs. ascending loop of the Loop of Henle

Descending Loop: Permeable to water, impermeable to sodium

Ascending loop: impermeable to water, permeable to sodium

Overall effects of the Loop of Henle:

Filtrate volume decreases, output is slightly more dilute than input, and a large amount of salts are removed

What does the collecting duct do?

It balances the water concentration of the blood through hormonal control.

How does water move from the collecting duct to the capillaries in the collecting duct?

Osmosis

What does hypertonic mean?

There is a high solute concentration.

What is spermatogenesis?

The process of making sperm

Are sperm cells haploid or diploid?

Haploid.

Steps of spermatogenesis:

Mitosis, Meiosis 1, meiosis 2, Differentiation.

What two hormones are in both spermatogenesis and oogenesis?

FSH and LH