3 acetyl‑CoA, 2 NADH, 1 CO2

1 acetyl‑CoA, 2 NADH, 3 CO2

1 acetyl‑CoA, 1 NADH, 1 CO2

2 acetyl‑CoA, 2 NADH, 2 CO2

2 CO2, 3 NADH, 1 FADH2, 1 ATP

2 CO2, 3 NADH, 1 FADH2, 2 ATP

2 CO2, 2 NADH, 2 FADH2, 1 ATP

2 CO2, 2 NADH, 1 FADH2, 2 ATP

Ethanol or lactose

Ethanol or lactate

Ethanol or glucose

Ethanol or uric acid

1

4

2

3

Glycolysis

Methylation

Krebs cycle

Pyruvate oxidation

The oxygen requirement of aerobic respiration is lower than that of fermentation

Aerobic respiration products such as CO2 and H2O do not harm the cell

For the same energy yield, aerobic respiration consumes organic matter more efficiently

Aerobic respiration is common in many plant tissues

The stomach conducts mechanical and chemical digestion

The large intestine performs both mechanical and chemical digestion

The mouth performs mechanical and chemical digestion

The small intestine performs mechanical and chemical digestion

Extracellular digestion (enzymes hydrolyze complex nutrients in the cavity) and intracellular digestion

By muscular squeezing of the cavity wall only, turning complex nutrients into simple ones

Only intracellular enzymatic hydrolysis of complex nutrients into simple nutrients that are absorbed

Extracellular digestion by enzymes acting in the cavity alone

Mechanical changes only, becoming simple nutrients absorbed into blood

Mechanical and chemical changes, becoming simple nutrients absorbed into blood

Chemical changes only, becoming simple nutrients absorbed into blood

Mechanical and chemical changes, becoming simple nutrients absorbed into lymph throughout the body

Nutrients moving after chemical digestion from the alimentary canal into blood only

Nutrients moving after digestion from organs of the canal into the circulatory system and then to the heart

Nutrients moving out from digestive organs into the bloodstream and lymphatic system

Nutrients moving after digestion from the canal into lymph only

Esophagus

Stomach

Small intestine

Large intestine

Food intake → digestion → absorption of nutrients → assimilation of substances

Food intake → digestion → assimilation of substances → absorption of nutrients

Food intake → digestion of substances → absorption of nutrients

Food intake → absorption of nutrients → digestion → assimilation of substances

Food is digested only extracellularly

Food is digested only intracellularly

Food enters the body cavity then is digested only by lysosomal enzymes

Food is digested both extracellularly and intracellularly

Lysosomes on the cavity wall

Muscle cells on the cavity wall

Gland cells on the cavity wall

The cavity lumen

Mouth → small intestine → stomach → pharynx → large intestine → anus

Mouth → esophagus → stomach → small intestine → large intestine → anus

Mouth → stomach → small intestine → large intestine → anus

Mouth → small intestine → stomach → esophagus → large intestine → anus

To achieve the highest efficiency of digestion

To allow sufficient time for cellulose digestion

To minimize energy use

To contain many organisms with many digestive enzymes

Animals capture food in two ways only: filtering and sucking

Many animals must search for food and migrate to find it

Animals that capture food by sucking have mouthparts suited to filtering and sucking fluids

Animals capture food only according to habitat type

In animals without specialized digestive organs, food is digested extracellularly

In animals with an alimentary canal, food is digested only extracellularly

In intracellular digestion, food is digested extracellularly and intracellularly

Intracellular digestion refers to digestion of food outside the body by enzymes acting on skeletons

They are immediately absorbed into body tissues

Food digested extracellularly aids absorption

Lysosomal enzymes of the phagocytic cells break them down into simple nutrients usable by the body

They are expelled from the cell to be digested in the cavity

Mouth

Food

Cells on the cavity wall secreting digestive enzymes

Partly digested food continues to be digested intracellularly

Gastrovascular cavity

Mouth

Food

Cells on the cavity wall secreting digestive enzymes

Partly digested food continues to be digested intracellularly

Gastrovascular cavity

Mouth

Food

Cells on the cavity wall secreting digestive enzymes

Partly digested food continues to be digested intracellularly

Gastrovascular cavity

Mouth

Food

Cells on the cavity wall secreting digestive enzymes

Partly digested food continues to be digested intracellularly

Gastrovascular cavity

Mouth

Food

Cells on the cavity wall secreting digestive enzymes

Partly digested food continues to be digested intracellularly

Gastrovascular cavity

Moves food along the canal and absorbs nutrients

Eliminates feces

Stores water and some mineral salts and forms feces

Grinds and mixes food with saliva; tongue mixes food and teeth are wetted by saliva

Moves food from the mouth down to the stomach

Eliminates feces

Stores water and some mineral salts and forms feces

Grinds and mixes food with saliva; tongue mixes food and teeth are wetted by saliva

Moves food along the canal and absorbs nutrients

Eliminates feces

Stores water and some mineral salts and forms feces

Contracts to grind and churn food with gastric juice

Continuously moves food along, absorbs nutrients

Eliminates feces

Stores water and some mineral salts and forms feces

Moves food from the mouth down to the stomach

Continuously moves food along, absorbs nutrients

Eliminates feces

Absorbs water and some mineral salts and forms feces

Moves food from the mouth down to the stomach

Continuously moves food along, absorbs nutrients

Eliminates feces

Stores water and some mineral salts and forms feces

Moves food from the mouth down to the stomach

O2 only

CO2 only

O2 and CO2

O2 intake and CO2 release

Body surface

Tracheal (air tube) system

Gills

Lungs

Across the body surface

Via tracheal tubes

Using gills

Using lungs

Across the body surface

Via tracheal tubes

Using gills

Using lungs

Sea turtle

Lion

Field mouse

Frog

Across the body surface

Via tracheal tubes

Using gills

Using lungs

Across the body surface

Via tracheal tubes

Using gills

Using lungs

Wildcat

Shrimp

Tree sparrow

Frog

Mouth closes; operculum lifts; operculum opens

Mouth closes; operculum lifts; operculum closes

Mouth opens; operculum lowers; operculum opens

Mouth opens; operculum lowers; operculum closes

Taking in O2 from the environment to supply cellular respiration, producing energy for life activities

Taking in CO2 from the environment to supply cellular respiration, producing energy for life activities

Excreting CO2 generated by external chemical reactions to balance the external environment

Taking in O2 and releasing CO2 to help balance the external environment

Gas-exchange organ

Respiratory surface

Gas-exchange pressure

Gas-exchange volume

Exchange of gases through gills

Exchange of gases through the tracheal system

Exchange of gases through the skin

Exchange of gases through lungs

The largest air tube is the trachea, forming a large respiratory surface

There are many ducts; movement of air is by diffusion only, not through spiracles

The respiratory tubes open at spiracles and can be actively ventilated

Air flows into a closed cavity so gases cannot exit through spiracles into tracheae

Gills receive blood from the heart, including filament and lamella

Each gill arch bears two hemibranchs; each hemibranch has many filaments with lamellae

The gill consists of two arches, each arch has four filaments, each filament has many lamellae

The branchial system on the operculum exchanges O2 and CO2 with water via the opercular cavity

Water rich in O2 moves along the gills in a single direction simultaneously with blood flow, not interrupted

Water rich in O2 moves along the gills in one continuous direction, not interrupted

Water rich in CO2 moves along the gills in one direction simultaneously with blood flow, not interrupted

Water rich in CO2 moves along the gills in a continuous single direction, not interrupted

Because they have lungs, so they can live in water and also jump on land

Because they have skin with many glands, so they can breathe in water and hop on land

Because they have both lungs and moist skin capable of respiration

Because they have gills, so they can breathe in water and crawl on land

Alveoli create hundreds of millions of alveolar sacs

The bronchial tree creates thousands of bronchioles

The lungs have many lobes and fissures

The respiratory system has many branches and divisions

Intercostal muscles and diaphragm

Abdominal wall and shoulders

Neck muscles and scapular muscles

Intercostal muscles and back

Circulatory fluid, heart and blood vessels

Circulatory fluid, heart and lymph

Heart, blood and the hematopoietic system

Blood, lymph and the immune system

The heart pumps blood into arteries under high pressure

Blood flows continuously in a closed vascular network; arteries → capillaries → veins → heart

Blood flows continuously in a closed vascular network; heart → arteries → capillaries → veins → heart

Blood moves directly from the heart to tissues and returns to the heart without vessels

Fish, lampreys, hagfish

Frog, lizard, crocodile

Birds, cats, cows, rabbits

Clam, snail, crab

Humans have oxygenated blood flowing through the gills

Humans have two circuits of circulation while fish have only one circuit

Humans have a closed system while fish have an open system

Humans have no valves in the heart while fish do

The atrium receives blood returning to the heart

The ventricle connects to arteries

Between atria and ventricles as well as at the bases of large arteries are valves

The heart wall is built from cardiac muscle cells

Sinoatrial node → atrioventricular node → bundle of His → Purkinje network → ventricles and ventricular myocardium

Atrioventricular node → sinoatrial node → bundle of His → Purkinje network → ventricles and ventricular myocardium

Sinoatrial node → bundle of His → atrioventricular node → Purkinje network → ventricles and ventricular myocardium

Sinoatrial node → Purkinje network → atrioventricular node → bundle of His

Atrial systole 0.3 s; ventricular systole 0.1 s; total diastole 0.4 s

Atrial systole 0.1 s; ventricular systole 0.3 s; total diastole 0.4 s

Atrial systole 0.1 s; ventricular systole 0.4 s; total diastole 0.3 s

Atrial systole 0.4 s; ventricular systole 0.1 s; total diastole 0.3 s

Blood pressure is the speed of blood flow measured per minute

Blood pressure is the force of the heart contracting against arteries

Blood pressure is highest in the aorta and large arteries, decreasing across smaller arteries and capillaries

Blood pressure is lowest in the aorta and higher in capillaries

Few capillaries, so diffusion is faster

Very numerous capillaries creating a large surface area for exchange

Thick, multilayered walls to prevent leakage

Very fast blood flow to speed exchange

Nervous and endocrine regulation

Endocrine and cellular regulation

Nervous regulation

Body fluids regulation

Liver

Kidney

Lung

Pancreas

Lung

Heart

Liver

Kidney

High pressure, fast flow

Low pressure, slow flow

High pressure, slow flow

Low pressure, fast flow

Heart → arteries → capillaries → veins → heart

Veins → capillaries → arteries → heart

Arteries → veins → capillaries → heart

Capillaries → arteries → veins → heart

Worms, snails, grasshoppers

Birds, cats, cows

Insects, fish, worms

Fish, frogs, reptiles

Arteries

Capillaries

Veins

Cardiac chambers

Sinoatrial node → atrioventricular node → bundle of His → Purkinje network

Atrioventricular node → sinoatrial node → bundle of His → Purkinje network

Sinoatrial node → Purkinje network → atrioventricular node → bundle of His

Bundle of His → sinoatrial node → Purkinje network → atrioventricular node

Highest in capillaries, lowest in veins

Highest in arteries, lowest in capillaries

Highest in arteries, lowest in veins

Highest in veins, lowest in arteries

From veins through capillaries

From arteries through capillaries

From the atrium to the ventricle

From the ventricle to the atrium

Blood flow rate is affected by pressure and the action on the vessel wall

The circulatory system of insects consists of two main parts: heart and vessels

Venous blood pressure is lowest

Negative pressure is well matched to the lowest value

True

False

Blood in arteries flows at low pressure and slow speed

Groups of animals that are very active usually have open circulation

Open circulation does not directly participate in transporting O2 and CO2

Open circulation does not directly contact body cells

2

1

3

4

Blood flows in arteries at high pressure

Blood directly contacts tissue cells

High flow rate enables long-distance transport

Capillaries are thin with one cell layer, allowing efficient exchange

Adaptive immunity

Cell-mediated immunity

Humoral immunity

Non-specific immunity

Adaptive immunity

Natural immunity

Innate immunity

Non-specific immunity

Acidic mucus in the stomach; low pH

Lysosomes in saliva and pepsin enzymes in the stomach

Drinking water helps wash away pathogens

Beneficial bacteria always compete with harmful bacteria

Acidic mucus; low pH in airways

Lysosomes in saliva and pepsin enzymes in the stomach

Body heat in sweat; fungus, viruses and bacteria develop

Beneficial bacteria always compete with harmful bacteria

Toxin

Antibody

Antigen

Hormone

Antigen

Antibody

Antigenic determinant

Allergen

Adaptive immunity

Cell-mediated immunity

Humoral immunity

Natural immunity

Plays a key role in T cell responses

T cells produce proteins that destroy foreign antigens

Important in viral diseases; T cells play an important role

Occurs in all organisms and even plants

Natural barriers of skin and mucosa

Secretions like mucus, tears, saliva

Preventive methods treat diseases for the body

Do not depend on the number of pathogens

Natural defenses of skin and mucosa

Phagocytic white blood cells and complement proteins

Specific immune response

Non-specific immune response

They cannot produce antibodies to fight pathogens

Their phagocytes are reduced; they cannot trap bacteria

White blood cells are destroyed, reducing non-specific immunity

T helper cells are destroyed, reducing both cell-mediated and humoral immunity

Virus resistance always changes so T cells become cytotoxic and secrete toxic substances

Viral antigens frequently mutate causing T cytotoxic cells to lose function

Viral antigens frequently mutate so B cells cannot recognize viral strains

Viral antigens frequently mutate so both cytotoxic T cells and B cells cannot recognize different influenza strains

It creates primary immune responses so, upon re-exposure to the antigen, memory B cells trigger a secondary response

It creates primary cell-mediated responses so, upon re-exposure, the antigen triggers T memory cells

It creates primary humoral responses so, upon re-exposure, an adaptive cell-mediated response is formed

It creates primary cell-mediated responses so, upon re-exposure, an adaptive humoral response is formed

Digestion

Circulation

Excretion

Cellular respiration

Intestine

Skin

Lungs

Kidneys

Intestine

Skin

Lungs

Kidneys

Intestine

Circulatory system

Skin

Lungs

Oxygen

Urea

Bilirubin

Carbon dioxide

True

False

The immune system immediately produces lysosomal enzymes

Mucus in the airway traps particles; cilia sweep them to the pharynx and stomach

Airway and lung pH is low, inhibiting pathogens

Nasal hairs and tight epithelial junctions in the nasal cavity prevent entry

Phagocytosis

Fever

Inflammation

Formation of antibodies

Cytotoxic T cells circulate and secrete proteins that kill antigens

They recognize signals from bacteria; are living substances

They weaken phagocyte activity

They inhibit bacteria and viruses from forming toxins

Adaptive immunity acts quickly like bone marrow; non-specific has no effect

Specific immunity acts slower initially but gives a stronger response; non-specific gives immediate response

Specific immunity is effective against diverse pathogens whereas non-specific is not

Specific immunity happens within each individual’s lifetime, non-specific exists from birth

T helper cells need cytokines from interactions with B cells

T helper cells need cytokines from interactions with antigen-presenting cells

T helper cells need cytokines from interactions with macrophages

T helper cells need cytokines from interactions with cytotoxic T cells

True

False

Occurs when the immune response is too strong to harmless antigens

Symptoms are mainly due to histamine

All allergic responses are anaphylactic shock

Degree of allergic reaction depends on the dose of allergen

Cells leave the original site and are removed by other body organs

Cells detach and are carried via blood or lymph to other sites forming malignant tumors

Cells detach and destroy other pathogens at the site

Cells move to other organs and enhance immune capacity of that organ

They cannot produce antibodies against Mycobacterium tuberculosis

Phagocytes are reduced; they cannot trap bacteria

White blood cells are destroyed, reducing non-specific immunity

T helper cells are destroyed, reducing cell-mediated and humoral immunity

cell

tissue

organism

organ

static, with indicators fixed at one exact value

dynamic, with indicators tending to change and oscillate around a set point

static, with indicators tending to change and oscillate around many values

dynamic, with indicators tending to change and oscillate around many values

kidney

lung

liver

eye

nervous system and endocrine glands

organs such as kidneys, liver, and blood vessels

receptors or sense organs

muscles and glands

regulating water reabsorption in the kidney

maintaining normal blood glucose concentration

regulating Na+ reabsorption in the kidney

regulating blood pH

receptor → control center → effector → receptor

effector → control center → receptor → effector

control center → receptor → effector → control center

receptor → effector → control center → receptor

osmotic pressure increases and blood pressure decreases

osmotic pressure increases and blood pressure increases

osmotic pressure decreases and blood pressure increases

osmotic pressure decreases and blood pressure decreases

2

3

4

5

the internal environment is stabilized after the controller acts, sending a reversed influence to the receptor

the internal environment is stabilized before the controller acts, sending a reversed influence to the receptor

the effector changes conditions opposite to those before control, sending reversed influence to the receptor

the internal environment returns to normal before control, sending reversed influence to the receptor

blood osmotic pressure increases

blood osmotic pressure decreases

blood pH decreases

blood glucose concentration decreases

increasing glucose excretion in urine

storing glucose as lipid to prevent diffusion out of cells

enhancing glucose release from cells

enhancing glucose transport into cells

maintaining body temperature homeostasis

maintaining blood glucose homeostasis

maintaining blood pH homeostasis

maintaining blood osmotic pressure homeostasis

disturb homeostasis

damage cells and organs

lead to diseases

all of the above

renal corpuscle (glomerulus) and tubule

cortex and medulla

renal pedicle and Bowman’s capsule

glomerulus and renal pelvis

Water, nutrients, and necessary ions in the filtrate are reabsorbed by tubular cells back to the blood

Blood pressure pushes water and solutes from blood through filtration slits into Bowman’s capsule, creating glomerular filtrate

Toxins and some ions remaining are actively secreted by tubular cells into the filtrate

Urine is concentrated by reabsorbing water and solutes in the renal pelvis

1700 – 1800 L

170 – 180 L

15 – 20 L

1.5 – 2 L

effector and receptor only

receptor, effector, and external stimulus

receptor, control center, and effector

control center and effector only

The receptor receives a stimulus from the external environment of the body

The receptor converts the signal that causes the response at the effector

The control center transmits signals as neural impulses or hormones for the effector to produce a response

If a component of the homeostatic system malfunctions, normal activity will still maintain homeostasis

regulate concentrations of solutes such as proteins and glucose in plasma

regulate water and salt balance via filtration pressure of body fluids

maintain blood pH by secreting H+ into filtrate and reabsorbing $$\mathrm{HCO_3^-}$$ into blood

regulate blood gases by adjusting $$\mathrm{O_2}$$ and $$\mathrm{CO_2}$$

ureter

urethra

collecting duct

glomerulus

filtering blood and reabsorbing nutrients

regulating the amount of water and salts reabsorbed

removing toxic substances and excess wastes from the body

all of the above

receptors or sense organs

central nervous system

endocrine glands

organs such as kidneys, liver, lungs, heart, and blood vessels

pancreas → insulin → liver and body cells → blood glucose decreases

liver → insulin → pancreas → body cells → blood glucose decreases

pancreas → body cells → insulin → blood glucose decreases

insulin → liver and body cells → pancreas → blood glucose decreases

Regulation is carried out by the central nervous system or endocrine glands

[1] is the control center, [2] is the receptor, and [3] is the effector

Signals are transmitted from [2] to [3] as neural impulses or hormones

[5] is the feedback that reverses the influence back to the receptor

During exhalation the mouth closes, the buccal floor rises, and the operculum opens.

During exhalation the mouth closes, the buccal floor rises, and the operculum closes.

During inhalation the mouth closes, the buccal floor lowers, and the operculum opens.

During inhalation the mouth opens, the buccal floor lowers, and the operculum closes.

Insects lack capillary networks around their tracheae while birds have capillary networks around their air tubes.

Respiratory movements in insects and birds both rely on expansion and contraction of respiratory muscles to increase air volume.

In insects, cellular gas exchange occurs directly with the environment without involvement of a circulatory system, making exchange less efficient.

Insects lack respiratory pigments, whereas birds have respiratory pigments in the circulatory fluid.

2

3

4

5

1

2

3

4

2

3

4

5

3

4

5

6

In most animals the heart has four chambers: two ventricles and two atria.

A cardiac cycle has three phases: atrial systole, ventricular systole, and joint diastole.

The heart works throughout life without fatigue because it has an intrinsic conduction system that generates rhythmic impulses.

Each cardiac cycle includes a joint diastole phase, allowing the heart to work for life without tiring.

1

2

3

4

3

4

5

6

It blocks invasion by disease-causing agents.

It recognizes and secretes proteins that kill diseased cells.

It specifically recognizes, eliminates, and remembers particular pathogens.

It performs phagocytosis and breaks down pathogens.

Homeostasis maintains stability of the internal environment of the body.

Homeostasis is a dynamic equilibrium.

The homeostatic state is maintained by regulatory systems of homeostasis.

In homeostasis, indicators such as blood pressure, body temperature, and blood glucose remain fixed constants.

2

3

4

5

120 liters

150 liters

180 liters

200 liters

The conversion of chemical energy in glucose into ATP by mitochondria.

The process by which green plants use light energy to synthesize organic matter from carbon dioxide and water, releasing oxygen.

The uptake of nutrients from soil through roots.

The breakdown of organic matter in the presence of oxygen.

$$6\text{O}_2 + \text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 6\text{CO}_2 + 6\text{H}_2\text{O}$$

$$6\text{CO}_2 + 6\text{H}_2\text{O} \rightarrow \text{C}_6\text{H}_{12}\text{O}_6 + 6\text{O}_2$$

$$\text{C}_6\text{H}_{12}\text{O}_6 \rightarrow 2\text{C}_2\text{H}_5\text{OH} + 2\text{CO}_2$$

$$\text{NADPH} + \text{ATP} \rightarrow \text{glucose}$$

It converts light energy into chemical energy, produces organic matter, and releases oxygen that supports aerobic life.

It only provides minerals to plants through the soil.

It removes carbon dioxide without affecting oxygen levels.

It is responsible solely for plant respiration at night.

Pigments block light from reaching chloroplasts to prevent damage.

Pigments absorb light of different wavelengths and transfer energy to reaction centers for photosynthesis.

Pigments store glucose produced during photosynthesis.

Pigments catalyze the Calvin cycle reactions directly.

Eating primarily one favorite food group to simplify meals.

Maintaining a balanced, varied diet with limited sugar and fats while including vegetables, fruits, and whole grains.

Skipping breakfast to reduce daily calories.

Eliminating all carbohydrates from the diet.

Different foods supply different essential nutrients, so variety helps meet all requirements.

Diversity increases taste only, not nutrient intake.

A varied diet reduces water needs.

Eating many different foods always lowers calorie intake.

Combine healthy eating with regular physical activity.

Limit sugary, fatty, and ultra-processed foods while increasing vegetables, fruits, and whole grains.

Avoid all protein sources to reduce calories.

Maintain consistent meal patterns and portion control.

It is caused by a deficiency of red blood cells.

It is an overreaction of the immune system to harmless substances, leading to mediator release such as histamine and symptoms like itching or swelling.

It results from normal digestion of proteins and fats.

It is due to the body’s inability to produce insulin.

To measure the antibiotic’s effectiveness immediately.

To detect hypersensitivity to the antibiotic and reduce the risk of anaphylactic reactions.

To check blood glucose before treatment.

To improve absorption of the drug.

To punish students who skip classes.

To assess vaccination coverage and compliance, identifying gaps in disease prevention.

To advertise pharmaceutical products to students.

To replace all health classes with surveys.