Exam 1: Chapter 1: Animals and their Environments

Question 1

Homeostasis is a signature of what?

Answer 1

Highly evolved life like mammals!

Question 2

Mammals have high levels of what?

Answer 2

Internal constancy

Question 3

How do we know that mammals have high levels of internal constancy?

Answer 3

From studying other species with high levels of internal constancy

Question 4

What are some examples of factors that must be kept at a constant level in individual cells, organs, and the blood stream?

Answer 4

SCOOPTG: Sodium, chloride, oxygen, osmotic pressure, temperature, and glucose levels

Question 5

How is blood glucose level in mammals an example of a factor that must be kept at a constant level or a controlled variable?

Answer 5

The liver takes up glucose and stores it as glycogen in the liver. The glucose is released when blood glucose falls or as needed to keep a constant level in the blood and in individual cells in the body

Question 6

All cells in the body must keep a stable level of what?

Answer 6

GLUCOSE

Question 7

Why is it important to have a constant supply of glucose built up in the liver?

Answer 7

Because the liver can be depleted of glucose so we need to have some stored

Question 8

What cells need high levels of glucose?

Answer 8

Working cells AKA any cell that requires high levels of ATP, which is obtained from the break down of glucose

Question 9

What are some examples of working cells that require high levels of glucose and explain why they require it

Answer 9

• Neural cells
• Muscle cells: Why we see so much glycogen stored in the muscles cells
• RBCs: Makes lots of Hb and have specific glucose transporters bc they need a steady supply of glucose

Question 10

What are two types of mechanisms that are in place that automatically make changes to keep internal constancy?

Answer 10

Negative and positive feedback

Question 11

Why do we need regulatory mechanisms like negative and positive feedback?

Answer 11

We have set points/ controlled variables that are normal for homeostasis and if those levels change from their set points then the body need a mechanism to bring it back to normal levels

Question 12

What does negative feedback do?

Answer 12

It corrects changes that occur in controlled variables when they change from the set points

Question 13

What are some examples of controlled variables that are controlled by negative feedback?

Answer 13

Blood glucose and oxygen levels

Question 14

Negative feedback can essentially be considered the same as what?

Answer 14

Homeostasis!

Question 15

Homeostasis can essentially be considered the same as what?

Answer 15

Negative feedback!

Question 16

What positive feedback do?

Answer 16

The returning effect in the feedback loop improves or amplifies the effect of the input

Question 17

Explain how the muscle contractions involved in the birthing process are an example of positive feedback

Answer 17

• An action potential occurs in a nerve cell or during the birth process of mammals
• When there is a signal above the threshold, sodium channels open up causing an influx of sodium, making the cell less negative
• A small change in voltage across the membrane of the nerve cell can add up, making that change greater and causing a summation
• This causes muscular contractions which aid in expelling the fetus and induce hormonal signals that stimulate even more intense contractions that aid in the birthing process

Question 18

What are the steps in the Hodgkin cycle?

Answer 18

1. Initial depolarization
2. Opening of voltage- gated sodium (Na+) channels
3. increased flow of sodium, making the cell body/ neuron less negative
4. Further membrane depolarization occurs as the action potential goes down the axon

Question 19

What kinds of animals are exceptions to homeostasis and how are they the exception?

Answer 19

Hibernators, they do not regulate all of their internal factors individually

Question 20

What is the difference between regulation and conformity in terms of their energetic costs and their effects on cells?

Answer 20

Regulation costs way more energy, but it does allow cells to function in steady conditions vs conformity which is energetically cheap but the cells are subject to changes with environmental changes

Question 21

How do hibernators use conformity to save energy during hibernation?

Answer 21

To save energy they let their internal temperatures drop to match the air temperature .: THEY HAVE NO CONSTANT INTERNAL TEMPERATURE!

Question 22

What is the difference between the hibernation mechanisms of bears and mice

Answer 22

Bears have lots of stored fats in their diets and they use it to conserve energy during hibernation making their metabolic demands during hibernation much lower vs mice who do not have lots of stored fat, making their metabolic demands during hibernation much higher!

Question 23

What changes over time?

Answer 23

Our physiology, it responds to changes in the environment causing internally programmed changes

Question 24

Give an example of now someone’s physiology can change over time

Answer 24

An unfit person who does not have a lot of arm strength can change their physiology and develop fitness with repeated strength training and exercise

Question 25

In the heat acclimation study what were conditions like?

Answer 25

Walked for 100 min at 49°c or 100°f at a rate of 3.5 mph or 17 minute miles

Question 26

What is the relationship between size and gestation length?

Answer 26

As gestation length increases, body size tends to increase as well

Question 27

In terms of the relationship between bodes size and gestation length, what is an example of an animal that falls close to expected?

Answer 27

The bushbuck

Question 28

In terms of the relationship between body size and gestation length, what is an example of an animal that does not fall close to expected? Why did this happen?

Answer 28

The mountain reedbuck, it has developed a specialized gestation that is different from most

Question 29

In the heat acclimation study, how many men in the cohort were able to walk the whole 100 minutes in the hot environment the first day? Why? What kind of response was this?

Answer 29

None, they had low endurance at the time and that was the acute repsonse

Question 30

In the heat acclimation study, how many men in the cohort were able to walk the whole 100 minutes in he hot environemtn after the 7 day period? Why? What kind of repsonse was this?

Answer 30

23 out of the 24 men were able to do it because their endurance dramatically increased. This was the chronic response

Question 31

In th heat acclimation study, how was their endurance quantified?

Answer 31

Their endurance was measured as a way of quantifying their physiological ability to sustain moderate exercise under hot coniditons

Question 32

In the heat acclimation study, what kinds of immediate acute repsonses had to occur in order for their endurace to increase? (4)

Answer 32

SSHO

1. With increased exposure to heat, sweat rates increased and there was better blood flow to the skin, allowing for more evaporative cooling
2. With time they lost less salt
3. Heart rates during exercise decrease over time
4. More efficient oxygen intake

Question 33

In the heat acclimation study, what kinds of changes are more likely to cause changes in genotype/phenotype and lead to things like acclimation, adaptations, and evolutionary responses?

Answer 33

Long-term, chronic repsonses

Question 34

In the heat acclimation study, what are more sort of long-term chronic responses that we can over days/ weekks or longer periods of time? What can these responses lead to?

Answer 34

We can see more chronic responses, which are called acclimation or a type of phenotypic plasticity. These kinds of changes are more likely to lead to changes in genotype/ phenotype and ultimately evolutionary responses like evolution and create adaptation

Question 35

Like we saw in the heat acclimation study, what are chonric responses also called?

Answer 35

Acclimation

Question 36

Explain how newborn and adult hemoglobin is different and why it is an example of how physiology changes over time

Answer 36

Different genes are expressed at different stages in development and the events that occur during devleopment cause phenotypic changes -> Fetal Hb (which is not expressed in adults) binds oxygen differently than adult Hb bc in a fetal animal you have a mixture of oxygenated and deoxygenated blood, whereas adults dont have this mixture

Question 37

Unlike human babies, when birds hatch they are ready to go off and eat real food. Explain why this difference is and how it is an example of how physiology changes over time.

Answer 37

• For baby birds, they go through a lot of the processes that we go through after birth, while they are still going through development, so this includes things like synaptic pruning and apoptosis .: When they hatch they are ready to go out and eat real food
• For human babies, when they are born they are still going through lots of brain development and we still see lots of expression of genes in areas associated with brain development and apoptosis in the nervous system .: There are still lots of changes in gene expression happening when we’re born

Question 38

Explain how the mitotic status of cells and gene expression changes as we age

Answer 38

When we are developing obviously we want most of our genes being expressed to aid in our development, but as we get older that changes and we have far fewer genes being expressed. That is why most adult cells are post- mitotic

Question 39

What does it mean if a cell is post- mitotic?

Answer 39

It is not really undergoing cell division anymore

Question 40

What kinds of cells are considered to be post- mitotic? Explain why

Answer 40

• Connective tissue cells: Articular joints/ cartilage are all laid down during embryonic development
• Muscle tissue cells: Muscles can be remodeled, but they are not undergoing cell division

Question 41

Even though muscle cells are considered to be post-mitotic, what kinds of changes can be made to them?

Answer 41

Although muscle cells aren’t really dividing, they can be remodeled: You can increase bone density/ mass and msucle mass by working out

Question 42

Why are women going through menopause encouraged to exercise?

Answer 42

When women go through menopause, many of them tend to lose bone density/mass and muscle mass. Since muscle tissue cells aren’t readily dividing to help in maintaining bone desinty/ mass and muscle mass, they are encouraged to work out to maintain their bone density/mass and muscle mass

Question 43

What kinds of cells are still mitotic and are readily dividing in the adult mammal?

Answer 43

• Sex cells: Sperm and egg
• Skin cells
• Olfactory neurons

Question 44

Why are some immunizations given through the nose?

Answer 44

Olfactory neurons are still considered to be mitotic and readily dividing in the nose

Question 45

What is another example of physiology changes over time?

Answer 45

The hormonal changes that occur during puberty!!

Question 46

What do biological clocks allow us to do?

Answer 46

They give us the internal capacity to keep track of the passage of time AKA it’s how our body tells time and its synched with our internal environment

Question 47

What kind of changes to our biological clock allow for?

Answer 47

Causes periodic, clock- controlled changes in phenotype

Question 48

What does oxygen combine with in our bodies and what does it make?

Answer 48

Combines with hydrogen to make water

Question 49

How much much of the air we breath contains oxygen?

Answer 49

21%

Question 50

Water is the what?

Answer 50

The unversal solvent

Question 51

What are the 3 main functions of water in the body?

Answer 51

1) Required for blood, bodily fluids, and all cells
2) Bound to other proteins and macromolecules
3) Required for catalysis

Question 52

In deserts and hotter climates, what kind of adaptations may mammals have to help them conserve water and prevent water loss?

Answer 52

Some mammals living in deserts/ hotter climates have layers of lipids that help them to conserve water and prevent water loss, so other animals living in colder climates might not have this adaptation

Question 53

What are evolutionary processes?

Answer 53

A change in gene frequencies over time in a population of organisms that can lead to changes in genotype and phenotype

Question 54

What does natural selection lead to?

Answer 54

Adaptation or a trait

Question 55

What are two examples of nonadaptive evolution?

Answer 55

Genetic drift and the founder effect

Question 56

What does genetic drift allow for?

Answer 56

Allows for chance to effect gene frequencies

Question 57

What other kind of evolution can occur, what does it allow for and why does it happen?

Answer 57

Nonadaptive evolution can also occur and it allows less adaptive traits to come through becuase not all traits are adaptive and it often happens by chance bc natural selection DOES NOT account for everything!!

Question 58

Why did Darwin assume natural selection accounted for everything?

Answer 58

Because he didn’t know about genetics, knock out or gene silencing via iRNA

Question 59

How can we study adaptations and trait evolution now?

Answer 59

We now use genetic engineering to silence genes using knock out animals, iRNA and gene silencing to study adaptations and family trees to study trait evolution -> All things Darwin didn’t know about!