BIO 461 - Exam 2 - Important Information

Question 1

Digestive Systems PowerPoint

Question 2

Carnivore teeth vs Herbivore teeth

Answer 2

Carnivore teeth for procurement & tearing, not grinding.

Carnivore teeth are often sharp with incisors (stick into animal) and back teeth are for tearing flesh.

Herbivores you do not see long teeth; they do not need to stick their teeth into a grass blade. Sharp incisors to trim the grass. Molars are the flat teeth to grind the food. Some of our largest animals on land are eating the poorest quality foods.

Question 3

Any carnivore will have a large, single chambered stomach with high musculature (protein digestion begins in the stomach) and lots of HCl and pepsin produced. Cecum greatly reduced or absent.

Question 4

What is the challenge of being a vegetative herbivore?

Answer 4

They can’t digest cellulose! Use a
“fermentation vat.”

All you are consuming is cellulose. The problem is you cannot chemically digest cellulose. You are consuming a bunch of potential nutrition, but you cannot break the bond between glucose molecules to get to a simple macrostructure, and therefore cannot absorb it.

They get around this problem but using a fermentation vat: use of microorganisms to convert carbohydrates to alcohol (by yeast) or organic acids (by bacteria) under anaerobic conditions. You can absorb fatty acids. These animals must have relatively large fermentation vats. You cannot do it in the stomach (too much acid and pepsin (breaks down proteins)).

Question 5

Examples of Foregut fermenters

Answer 5

bovids
camelids
kangaroos
colobus monkeys
sloths
hoatzins

Question 6

Examples of Hindgut fermenters

Answer 6

elephants
horses
rodents
rabbits
grouse
iguanas
tortoises

Question 7

Compare foregut and hindgut fermenters

Answer 7

Foregut fermenters: If you have a gut, from your stomach to your rectum, if it is the foregut, the fermentation vat is at the very beginning before the gut (digestive tract).

• Consume a diet of almost all cellulose.
• The stomach greatly enlarged & divided into multiple chambers to process a meal.
• The ruminants (cows, etc.) is the ultimate foregut fermenter.

Hindgut fermenters: The fermentation vat is after the gut (digestive tract) at the end (near the colon or cecum).

*Consume a diet mostly of cellulose but with some digestible carbohydrates and proteins.
* Large intestine and/or cecum greatly enlarged and serve as fermentation chambers.

Question 8

What is the process for digestion in ruminants (e.g., cattle, sheep, goats, buffalo, deer, elk, antelope, giraffe)?

Answer 8

1. Rumen (fermentation)
2. Reticulum (trap and regurgitation)
3. Omasum (water & VFA absorption)
   * VFA primary energy source
4. Abomasum (true stomach - secretion of HCl, pepsinogen, & mucus)

Question 9

Rumen:

Answer 9

The fermentation vat. Does not have acids or pepsin. Warm, moist and has bacteria (cellulose and ammonia – ammonia helps build proteins to build more bacteria). Bacteria creates the amino acids, but needs nitrogen – every amino acid has a nitrogen at the end). As a waste product, it is going to create volatile fatty acids – easy to diffuse in the environment and crosses respiratory membranes. They will produce CO2 and CH3 (methane).

Question 10

Omasum:

Answer 10

There is water and urea (waste product to break down proteins) and bicarbonate (human pancreas produces it to buffer against acidity (HCl)).

Question 11

Abomasum:

Answer 11

∙ 3rd chamber – filtered water, volatile fatty acids, and bacteria.

∙ Cows eat cellulose, but absorb volatile fatty acids (majority of diet).

∙ Secretion of HCl, pepsinogen, and mucus – assist in the breakdown of bacteria to make proteins. The microbes take care of proteins and break them down into amino acids so the body can absorb it.

Question 12

Foregut fermenters:

• Passage time ______ hrs
• ______ efficiency (at extracting energy from food)

Hindgut fermenters:

• Passage time ______ hrs
• ______ efficiency at extracting energy from cellulose.

Answer 12

70-100 hrs
70-100% efficiency

15-30 hours
20-65% efficiency

Question 13

Correlation is going to be on the exam!

Answer 13

Digestion needs to happen fast, or else it is going to rot (your gut) if bacteria in the inside of the stomach of the anima it just ate begins to replicate. Microvilli are 75% longer (75% more surface area / 75% more ability to absorb nutrients that are pouring in as the meal is being digested). The heart is in the pathway of the meal moving down; so, it moves down the pathway and then moves back up. By having the heart be able to move, you are reducing the amount of time that the heart is against the meal, making it easier to swallow that meal, and make it a more effective way to pump.

Question 14

What 3 things does a “dynamic digestive tract” increase?

Answer 14

• increase intestine length → ↑SA
• increase villi/microvilli number & length → ↑SA
• increase enzymatic activity → increase nutrient absorption capability

Question 15

Renal Systems PowerPoint

Question 16

Two important factors in protein metabolism.

Answer 16

1. ammonia (NH3) is highly toxic, accumulation in body is quickly fatal.
2. Urea is relatively expensive to produce, but much less toxic.
   Still problematic at high concentrations, so need to remove it from the blood relatively quickly.

Ammonia is a toxic waste product produced when the body breaks down proteins, while urea is a non-toxic compound created by the liver to convert ammonia into a form that can be safely excreted from the body through urine; essentially, urea is the body’s way of processing and eliminating ammonia.

Question 17

processes involved in making urine in the mammal kidney nephron

Answer 17

1) filtration of blood - passive and minimally selective process
2) reabsorption of valuable components from the filtrate; active & passive
3) active secretion of additional wastes from the blood into the filtrate; active

Answer 18

If you want to be able to concentrate your urine in your kidney, beyond that of the concentration of plasma, you must have the loop of Henle. Without the loop of Henle, you have no concentrate gradient in your medulla. Without that, opening water channels will not do anything. If an animal does not have a loop of Henle, they can remove the waste, but it is not concentrated. They will lose a lot of water leaving the kidneys.
With hormone stimulation, urine leaving the kidney can be <1% of the glomerular filtrate that entered the nephron!

Question 19

Which animals have a Loop of Henle?

Answer 19

Have: Mammals, birds, and some reptiles.

Do not have: fish, reptiles and amphibians.

Question 20

Who can excrete more nitrogenous waste?

Whose kidneys can more effectively concentrate the nitrogenous waste?

Mammal kidneys are the most effective at __________, reptiles are the most efficient at _______________________________.

Answer 20

Reptile.

Mammals. Mammals do it in the kidneys (loop of Henle) versus the reptile did this after the fact (colon or bladder).

concentrating urine
eliminating concentrated nitrogenous waste.

Question 21

Compare the Amphibian, Reptile, Bird, and Mammal renal system.

Amphibian renal system

Answer 21

Amphibian renal system
low # of glomeruli; can restrict flow through them – glomeruli filter waste through water, out of the blood and plasma. Without a high metabolism, you do not have a lot of waste; you do not need to do much filtration, and therefore, do not need a lot of glomeruli. They can constrict the afferent arterioles that lead to the glomeruli and limit flow through them, which impacts the ability to filter blood.
Cloaca: gathering of everything before it leaves (urine, feces, eggs, sperm).

Question 22

Compare the Amphibian, Reptile, Bird, and Mammal renal system.

Reptile renal system

Answer 22

Reptile renal system
post-renal water +/- sodium reabsorption can occur in the colon (H2O absorption) or bladder (independent of ADH/vasopressin) – They can do this in the bladder because amphibians can do it in the bladder. The role of the large intestine / colon is water absorption. If you can do it from your feces, you can do it from your urine. Direct the urine into the colon and pull water out. Mammals cannot do this because your urine and feces do not connect. It would have to leave the body. The idea of having a cloaca has the advantage of taking this urine and send it to the colon.

Excrete nitrogenous waste as uric acid (urate)
- more than twice as costly to convert NH3 to uric acid than to urea
- precipitates as a salt; thus, excretion can be solid
The significant advantage of secreting a product that is much more costly to produce is that, unlike urea, that is highly soluble, uric acid precipitates as a salt and excreted as a solid. In the colon, they can pull all the water out of it, the uric acid will precipitate (highly concentrated) and water is brought back into the lizard and what is left is the salts.

Question 23

Compare the Amphibian, Reptile, and Bird renal system.

Bird renal system

Answer 23

Birds are endotherms, with a high metabolic rate = high waste production. Increase the ability to filtrate (producing more waste).
Every nephron in a mammal has a loop of Henle (some long and some short). Birds also have a reptile type (no loop of Henle). Therefore, they can concentrate their urine 1.5-3 times plasma (not as much as humans). They cannot sustain themselves just be concentrating urine in the kidney. There exogenous waste can be uric acid = advantage is that its concentrated (solid).

Question 24

Understand the difference between fresh water and salt water fish.

How they regulate sodium and how they regulate water so they do not balloon up.

Salt water has a higher osmolality. Salts are ions that contribute to the osmolality.

Question 25

Fresh Water Fish

Fish osmolality
Diffusion

Do fresh water fish need to drink?

Answer 25

fish osmolality (~300 mOsm) is greater than (>) water osmolality (<50 mOsm).
∙ diffusion: lose ions & gain water through gills/skin.
∙ Fish have gills, with diffusion of oxygen, CO2, monovalent ions, ammonia, water. Gills have high permeability – concentration gradient will go from low osmolality to a high osmolality. Water wants to move from the environment into the fish across the gills. Water is constantly flowing into the fish.
∙ It takes a significant amount of energy to keep enough sodium in the body is a problem that cost them energy to deal with.

Do fresh water fish need to drink? No, tons of water are coming in through the gills. Fish do need to urinate a lot. Gaining water (due to the gradient) and the ions are moving from a high concentration to a low concentration. The ions are moving out as water is coming in.

Question 26

Salt Water:

Fish osmolality
Diffusion

Do salt water fish need to drink?

Answer 26

fish osmolality (~300 mOsm) less than (<) water osmolality (~1,000 mOsm)
∙ diffusion: gain ions & lose water through gills/skin
∙ Water is going to pour out of the fish, and ions are going to go into the fish.

Teleosts:
- drink continuously with little urination
- some have greatly reduced or no glomeruli
- actively secrete wastes & excesses into tubules
- actively transport Na+ out through gills

Question 27

Cartilaginous fish:

Answer 27

• high plasma urea levels raise osmolality to be slightly hyperosmotic to SW [so no water loss through gills].(plasma [urea] 2.5% vs. 0.01-0.03% in most other vertebrates).
• trimethylamine oxide (TMAO) protects fish from urea-induced protein destabilization
• don’t need to drink!
• excess NaCl actively excreted via rectal gland

Question 28

What are two ways an animal can get “hot” internally?

Answer 28

Generate a lot of heat by moving (+ being well insulated) and in a hot environment.

Question 29

Reproductive Systems PowerPoint

Question 30

estrus cycle vs. menstrual cycle

species
endometrial enlargement
if infertile cycle, endometrium is
bleeding/discharge associated with
receptivity

Answer 30

Estrus Menses

Most mammals apes & some monkeys
moderate extreme
reabsorbed partially sloughed
enlargement sloughing
peri-ovulation anytime

Question 31

What is the distinguishing character of all mammals?

What are three purposes for this?

Answer 31

mammary glands

1. enables mother to continue to provide nutrients & water to offspring after birth independent of environmental conditions
2. provides support of the immune function (especially in colostrum)
3. strengthens mother-offspring bond

Question 32

Why are there no marsupials with hooves, wings, or flippers?

Answer 32

They cannot climb up mom’s belly with hooves, wings, or flippers. You must have a grip. Every marsupial you see has front limbs as claws (hands) that can grip. One of the toes tends to be opposing or spread out wide.

Question 33

What is parthenogenesis? What are the advantages and disadvantages?

Answer 33

Reproduction from an ovum without fertilization.

Advantages:
* Greater annual output by the population (every offspring is female).
* No need for male presence
* Easier range expansion

Disadvantage:
* Minimal genetic diversity, so reduced evolutionary adaptation.

Question 34

Facultative vs obligatory reproduction

Answer 34

“Facultative reproduction” means an organism can switch between sexual and asexual reproduction depending on conditions, while “obligatory reproduction” refers to an organism that only reproduces through one method, either exclusively sexual or exclusively asexual, and cannot switch between the two.

Question 35

What is facultative parthenogenesis?

Answer 35

Facultative parthenogenesis refers to the ability of a species that typically reproduces sexually to occasionally produce offspring asexually, meaning a female can generate offspring without needing a male, but can still choose to reproduce sexually when conditions allow; essentially, it is the capability to switch between sexual and asexual reproduction depending on the circumstances.

Question 36

Compare internal and external fertilization

What is external fertilization and what 3 things does it require?

Answer 36

sperm and ova combined happens outside of the animal.

Requires:
- males & females together at oviposition
- egg without a shell
- water (or very high moisture)

Question 37

Compare internal and external fertilization

What are the 4 advantages of internal fertilization

Answer 37

• no dilution of sperm
• controlled environment
• allows for shelled eggs
• allows for viviparity (live birth)
• typically requires a copulatory organ

Question 38

Compare primitive eggs and amniotic eggs

Primitive eggs (fish, amphibians)

How does this impact the potential embryo size of the embryo?

Limitations:

Answer 38

Primitive eggs (fish, amphibians)
∙ embryo encased in a thin membrane which is surrounded by a jelly coat
∙ nutrients stored in a yolk sac (extra-embryonic membrane) – produced by the embryo outside of itself.
∙ highly permeable; gas provisioning to embryo dependent on diffusion

How does this impact the potential embryo size of the embryo? If you have a big egg, the diffusion difference increased, and diffusion is influenced by the thickness of the barrier. You would not get enough diffusion for something that needs more oxygen.
∙ waste also eliminated via diffusion
∙ wiggle through membrane & jelly coat to hatch

Limitations:
∙ highly susceptible to dehydration
∙ must be small to limit diffusion distance
∙ vulnerable to predation

Question 39

Compare primitive eggs and amniotic eggs

Amniotic egg (chicken egg) required for?

Parts of an amniotic egg

Shell provides what 3 things?
Yolk and albumin
What 3 things does the albumin provide?

How do amniotic eggs get fertilized?

Answer 39

Amniotic egg (chicken egg): required for external development in non-wet environments; if you lay a primitive egg in a dry environment, it is going to shrivel up. You need something to protect it from desecration.
1. Shell provides:
∙ a barrier to diffusion
∙ reduces water loss
∙ structural support & protection – hard to break the egg – structural advantage over soft primitive eggs.
∙ mineral supplies to embryo – a lot of calcium in the shell.
2. Yolk – nutrients for the embryo
3. Albumin
∙ additional nutrients for embryo
∙ water for embryo
∙ protection from microbes – passes out through the cloaca with feces.
 physical: viscous
 chemical: protease inhibitors, nutrient sequesters, a lytic enzyme, and antibodies

How do amniotic eggs get fertilized? Requires internal fertilization (before the shell is put on).

Question 40

Viviparity (live birth) benefits and costs

Answer 40

Benefits:
- controlled developmental environment
- defense of embryos from predators
- extends duration of nutrient provisioning to offspring

Costs:
- requires extended parental involvement
- physical burden, slows parent

Question 41

Why is vivapartiy partental care vs not parental care?

Answer 41

Viviparity is considered a form of parental care because it involves the development of an embryo inside the mother’s body, where she actively provides a protected environment and nourishment to the growing offspring throughout its development, essentially “caring for” the young while they are still inside her, unlike oviparous species that lay eggs and provide minimal to no care after laying them.

Direct nourishment:
The mother’s body supplies nutrients to the developing embryo via the placenta, allowing for a higher chance of survival compared to external egg development.
Protection from predators:
By carrying the young inside her body, the mother shields them from potential threats in the environment.
Controlled environment:
The mother can regulate the temperature and conditions within her body to optimize the development of the offspring.

Question 43

frog metamorphosis
herbivory → carnivory

Answer 43

major mouth remodeling:
lose keratinized beak
elongate jaws
develop teeth
develop tongue muscles & support

develop stomach
shorten intestine

major remodeling of skull
- eye protrusion
- grow eye muscles

Question 44

mammal urinary tract

Answer 44

high metabolic rate → high waste production
need to remove large amounts of wastes rapidly

• nitrogenous waste excreted as urea
  highly soluble, so secreted as a liquid. Even if water is limited, the animal needs to lose water to eliminate nitrogenous waste
• long loops of Henle enable the collecting ducts to concentrate urine 5-25X that of plasma to limit the amount of water than needs to be excreted
• bladder stores urine prior to elimination

Question 45

Why store the urine?

Answer 45

1. enables intermittent release despite constant production
2. social uses of urine (e.g., communication)

Question 46

reptile renal system

Answer 46

low metabolic rate → low waste production
- nephron: (compared to amphibians)
- smaller & fewer glomeruli → less filtration (losing water)
- longer tubules (more time to bring back things you need), so greater water reabsorption
- no loops of Henle, so isosmotic
- ureters empty into cloaca, and then retrograde into large intestine or bladder (bladder present in most turtles & some lizards; not in snakes & crocs)
- post-renal water +/- sodium reabsorption can occur in the colon (H2O absorption) or bladder (independent of ADH/vasopressin)
- excrete nitrogenous waste as uric acid (urate)
- more than twice as costly to convert NH3 to uric acid than to urea
- precipitates as a salt; thus, excretion can be solid

Question 47

Bird renal system (1)

Answer 47

20x nephrons of reptiles, 2x that of mammals
- glomerular filtration rate ~4x blood volume/day (mammals 8-100x) not a high as mammals
- combination of reptile-like (small glomerulus, no loop of Henle) and
mammal-like (moderate size glomerulus, long loop of Henle) nephrons
- proportion varies among species (10-35% mammalian type)
- can concentrate urine 1.5-3x plasma (mammals 5-10x, up to 25x)

Question 48

Bird Renal system (2)

Answer 48

nitrogenous waste is uric acid, but not as solid as it is in lizards when excreted
- post-renal water and ion reabsorption in cloaca or large intestine
- no bladder
- however, in ostriches, the coprodeum out-pockets from the cloaca and colon (creating a pseudo-bladder)
- ion excretion supplemented by salt glands in many, particularly marine, species

Question 49

cutaneous water transfer

advantages of highly permeable skin:

Answer 49

1. cutaneous respiration
2. absorb water via osmosis (don’t need to drink)

frogs/toads:
- pelvic patch
- skin more granular & vascular
- uptake increased by vasopressin (ADH)
- up to 80% of water absorption in toads
- enables mouth to be specialized for feeding

Question 50

in general, ______ have higher water demands relative to ______.

• live near water source OR
• extremely mobile

Answer 50

endotherms / ectotherms

Question 51

Why breed at different times of year?

Answer 51

environmental regulators of reproductive activity:
- temperature (typical of reptiles)
- photoperiod (typical of mammals & birds)
- rainfall (typical of amphibians, but also others)