Animals: Structure and Function: Test Review

Everything for the Unit 4 test on one page: the key facts from all 6 lessons, the mistakes that cost the most marks, and a practice test that points you back to the lessons you need.

Key facts

The Digestive System

Mechanical digestion (chewing, churning, emulsifying) increases surface area; chemical digestion (enzymes, acid) breaks bonds by hydrolysis.
Carbohydrates become monosaccharides, proteins become amino acids, and lipids become fatty acids and glycerol.
Starch digestion begins in the mouth (salivary amylase), protein digestion in the stomach (pepsin, pH about 2), and fat digestion mainly in the small intestine (lipase helped by bile).
Villi and microvilli give the small intestine a huge surface area for absorption; sugars and amino acids enter capillaries, fats enter lacteals.
The large intestine absorbs remaining water and houses bacteria that make vitamin K.
Food energy: about 4 Cal/g for carbohydrate and protein and 9 Cal/g for fat.

The Respiratory System

Air path: nasal cavity, pharynx, larynx, trachea, bronchi, bronchioles, alveoli.
Inhalation: diaphragm and external intercostals contract, chest volume increases, lung pressure drops, air flows in.
Gases move across the alveoli by diffusion down a concentration (diffusion) gradient; no energy is used.
Hemoglobin in red blood cells carries almost all oxygen; each molecule can carry up to four $O_{2}$ .
Minute ventilation = breathing rate × tidal volume; a typical resting breathing rate for healthy adults is about 12 to 20 breaths/min.
Rising blood carbon dioxide is the main stimulus that increases breathing rate.

The Circulatory System

Blood path: vena cavae, right atrium, tricuspid valve, right ventricle, pulmonary arteries, lungs, pulmonary veins, left atrium, bicuspid valve, left ventricle, aorta.
Arteries carry blood away from the heart and veins carry blood toward it, regardless of oxygen content; capillary walls are one cell thick for exchange.
The left ventricle has the thickest wall because it pumps blood through the whole systemic circuit.
Blood is about 55% plasma; red blood cells carry oxygen, white blood cells fight infection, platelets start clotting.
Blood pressure is systolic/diastolic, typically around 120/80 mmHg for a healthy adult; resting heart rate is typically about 60 to 100 beats/min.
Cardiac output = heart rate × stroke volume.

Dissection: How the Systems Fit Together

Anterior = toward the head, posterior = toward the tail, dorsal = back, ventral = belly; left and right are the specimen's own.
Cut skin with scissors tips up, open the specimen ventral side up, and separate tissues with a blunt probe.
The diaphragm divides the thoracic cavity (heart, lungs, trachea, esophagus, thymus) from the abdominal cavity (liver, stomach, intestines, pancreas, spleen).
Hepatic portal system: blood from the intestines goes to the liver before the heart.
Pulmonary circuit: right ventricle → pulmonary arteries → lungs → pulmonary veins → left atrium.
The Three Rs of animal use: Replace, Reduce, Refine.

Breathing, Circulation and Digestion Across the Animal Kingdom

Good respiratory surfaces are moist, thin, large in area and well supplied with blood; surface area to volume ratio falls as animals grow.
Gas exchange: skin (earthworms, frogs), gills (fish), tracheae (insects), lungs (most land vertebrates).
Countercurrent exchange in gills keeps a concentration gradient along the whole gill, extracting most of the oxygen from water.
Open circulation: hemolymph bathes organs at low pressure (insects). Closed circulation: blood stays in vessels at higher pressure (earthworms, vertebrates).
Hearts: fish 2 chambers (single circuit), amphibians 3, most reptiles 3 (partly divided), birds and mammals 4 (complete separation, supports endothermy).
Gastrovascular cavity has one opening; a complete tract allows specialization such as the crop, gizzard and the four-chambered ruminant stomach.

System Disorders and Medical Technology

The digestive and respiratory systems supply glucose and oxygen; the circulatory system delivers them to cells and removes carbon dioxide.
Asthma narrows the bronchioles (inflammation, muscle tightening, mucus); emphysema destroys alveolar walls, reducing the surface area for diffusion.
Most peptic ulcers are linked to Helicobacter pylori infection or long-term use of anti-inflammatory pain relievers, which let acid damage the stomach or duodenum lining.
Arteriosclerosis is the hardening and narrowing of arteries; a blocked coronary artery causes a heart attack, while cardiac arrest is an electrical failure of the heartbeat.
CT uses X-rays (ionizing radiation); MRI uses magnetic fields and radio waves; endoscopes look inside the digestive tract directly.

Where marks get lost

Calling bile an enzyme. Bile emulsifies fat into droplets (mechanical digestion); lipase is the enzyme that actually breaks fat molecules apart. (The Digestive System)
Saying the stomach is where most nutrients are absorbed. The stomach mainly churns food and starts protein digestion; almost all nutrient absorption happens through the villi of the small intestine. (The Digestive System)
Listing the liver or pancreas as part of the path food travels through. Food passes only through the digestive tract; the liver, gallbladder and pancreas deliver secretions into it through ducts. (The Digestive System)
Thinking denatured enzymes recover when conditions return to normal. A cold enzyme speeds up again when warmed, but an enzyme denatured by high heat has lost its shape and generally stays inactive. (The Digestive System)
Saying chewing turns starch into sugar. Chewing only makes pieces smaller; it is salivary amylase that chemically changes starch into maltose. (The Digestive System)
Saying the lungs expand on their own and suck air in. The lungs have no muscle for this; the diaphragm and intercostal muscles enlarge the chest, and the resulting pressure drop lets air flow in. (The Respiratory System)
Saying oxygen is pumped into the blood. Gas exchange is diffusion down a concentration gradient and needs no energy from the body; breathing and blood flow simply keep the gradient steep. (The Respiratory System)
Thinking exhaled air contains no oxygen. Exhaled air is still about 16% oxygen, which is why rescue breaths can supply oxygen to another person. (The Respiratory System)
Mixing up respiration and breathing. Breathing (ventilation) moves air; cellular respiration is the chemical process in mitochondria that uses oxygen and releases carbon dioxide. (The Respiratory System)
Believing low oxygen is the main trigger to breathe. The breathing centre responds mainly to rising carbon dioxide (lower blood pH), which is why holding your breath becomes uncomfortable quickly. (The Respiratory System)
Defining arteries as vessels that carry oxygen-rich blood. Arteries carry blood away from the heart; the pulmonary arteries carry oxygen-poor blood to the lungs, and the pulmonary veins carry oxygen-rich blood back. (The Circulatory System)
Mixing up left and right on heart diagrams. Diagrams are drawn as if you face the person, so the left ventricle appears on the right side of the page. (The Circulatory System)
Believing blood in veins is blue. Oxygen-poor blood is dark red; veins only look bluish through the skin, and diagrams use blue simply as a code. (The Circulatory System)
Assuming heart muscle gets its oxygen from blood inside the chambers. The heart wall is supplied by its own coronary arteries, which is why a blocked coronary artery damages heart muscle. (The Circulatory System)
Reversing systolic and diastolic. Systolic (the higher number, written on top) is during contraction; diastolic (the lower number) is during relaxation. (The Circulatory System)
Using your own left and right instead of the specimen's. With the pig on its back facing you, its left side is on your right. (Dissection: How the Systems Fit Together)
Cutting deep with a scalpel to open the body cavity. Use scissors with the tips pointed up so you cut skin and muscle without slicing the organs underneath. (Dissection: How the Systems Fit Together)
Confusing the trachea and the esophagus. The trachea has stiff cartilage rings and is ventral; the esophagus is soft, collapsible and dorsal. (Dissection: How the Systems Fit Together)
Thinking blood from the intestines goes straight to the heart. It goes first to the liver through the hepatic portal vein. (Dissection: How the Systems Fit Together)
Assuming the pulmonary veins carry oxygen-poor blood because they are veins. Veins are defined by direction (toward the heart); pulmonary veins carry oxygen-rich blood. (Dissection: How the Systems Fit Together)
Thinking insect blood carries oxygen the way ours does. In insects, the tracheae deliver air directly to the cells, and the hemolymph mainly carries nutrients and wastes. (Breathing, Circulation and Digestion Across the Animal Kingdom)
Describing countercurrent exchange as water and blood flowing the same way. The whole point is that they flow in opposite directions. (Breathing, Circulation and Digestion Across the Animal Kingdom)
Saying a fish's two-chambered heart pumps blood to the gills and body separately. Fish have one circuit: blood goes from the heart to the gills and then directly on to the body. (Breathing, Circulation and Digestion Across the Animal Kingdom)
Believing cows make enzymes that digest cellulose. Microbes in the rumen do the digesting; the cow absorbs the products and digests the microbes. (Breathing, Circulation and Digestion Across the Animal Kingdom)
Assuming bigger animals can rely on their skin because they have more skin. Their surface area to volume ratio is lower, so skin alone supplies too little oxygen per cell. (Breathing, Circulation and Digestion Across the Animal Kingdom)
Treating heart attack and cardiac arrest as the same thing. A heart attack is a blocked coronary artery; cardiac arrest is the heart's electrical rhythm failing so it stops pumping. (System Disorders and Medical Technology)
Saying most stomach ulcers are caused by stress or spicy food. Most are linked to Helicobacter pylori infection or long-term use of anti-inflammatory pain relievers; stress and spicy food can worsen discomfort but are not the main causes. (System Disorders and Medical Technology)
Confusing asthma with emphysema. Asthma narrows the bronchioles and flare-ups can often be relieved; emphysema permanently destroys alveolar walls and cannot be reversed. (System Disorders and Medical Technology)
Assuming every scan uses radiation. CT uses X-rays (ionizing radiation), but MRI uses magnetic fields and radio waves, and ultrasound uses sound waves. (System Disorders and Medical Technology)
Describing a disorder as affecting only one system. Because the systems are linked, emphysema also strains the heart, and narrowed arteries reduce oxygen delivery to every organ, including the digestive tract. (System Disorders and Medical Technology)

Practice test

24 questions from across the unit. Each one shows the lesson it comes from.

The Digestive System
1
Where does the chemical digestion of protein begin?
The Digestive System
2
For the same serving (12 g fat, 30 g carbohydrate, 10 g protein, 268 Cal in total), what percentage of the energy comes from fat? Give your answer to one decimal place.
%
The Digestive System
3
Name the finger-like projections of the small intestine lining that increase surface area for absorption.
The Digestive System
4
Why does the large intestine matter even though almost no digestion happens there?
The Respiratory System
5
What does the diaphragm do during inhalation?
The Respiratory System
6
A student's breathing rate is 15 breaths/min at rest and 36 breaths/min right after a run. By what percentage did the breathing rate increase?
%
The Respiratory System
7
Put these structures in the order air passes through them during inhalation.
1. 1Bronchi
2. 2Alveoli
3. 3Bronchioles
4. 4Nasal cavity
5. 5Pharynx
6. 6Larynx
7. 7Trachea
The Respiratory System
8
What process moves oxygen from the alveoli into the blood? (One word.)
The Circulatory System
9
Which chamber of the heart has the thickest muscular wall?
The Circulatory System
10
A person counts 21 pulse beats in 15 seconds. What is their heart rate in beats per minute?
beats/min
The Circulatory System
11
In a blood pressure reading of 120/80 mmHg, what is the name for the top number?
The Circulatory System
12
Match each blood component to its main function.
Red blood cells
White blood cells
Platelets
Plasma
Dissection: How the Systems Fit Together
13
In a fetal pig, which term describes the position of the kidneys relative to the intestines?
Dissection: How the Systems Fit Together
14
Match each organ to how you would recognize it in a fetal pig.
Liver
Spleen
Pancreas
Trachea
Gallbladder
Dissection: How the Systems Fit Together
15
Which vessel carries oxygen-rich blood?
Dissection: How the Systems Fit Together
16
Which action is an example of the "Replace" principle of the Three Rs?
Breathing, Circulation and Digestion Across the Animal Kingdom
17
Match each animal to its main gas-exchange surface.
Earthworm
Lake trout
Grasshopper
Beaver
Breathing, Circulation and Digestion Across the Animal Kingdom
18
Water entering a fish's gills holds 9.0 mg/L of oxygen and leaves with 2.7 mg/L. What percentage of the oxygen did the fish extract? Give a whole-number percentage.
%
Breathing, Circulation and Digestion Across the Animal Kingdom
19
What is the main disadvantage of a gastrovascular cavity compared with a complete digestive tract?
Breathing, Circulation and Digestion Across the Animal Kingdom
20
Why is a four-chambered heart linked to endothermy in birds and mammals?
System Disorders and Medical Technology
21
Why does emphysema reduce the amount of oxygen that reaches the blood?
System Disorders and Medical Technology
22
A coronary artery becomes blocked by plaque and a clot, and part of the heart muscle is deprived of oxygen. What is this event called?
System Disorders and Medical Technology
23
What is the name of the flexible tube with a light and camera that is used to look inside the stomach or colon?
System Disorders and Medical Technology
24
Match each technology to how it works.
MRI
CT
Ultrasound
Insulin pump