What causes an entire species to become extinct?

First, we must remember that it is Humanity, the scientific tendency toward taxonomy, that “defines” a species, or even a “family” of living organisms. Take, for example, Linnaeus’ system for dividing plants into types. While his first divisions are clear and understandable, his division of different species of roses gets pretty arbitrary, especially when we consider human-invented species. To answer your question, the causes of one species dying out while closely related species survive can...

First, we must remember that it is Humanity, the scientific tendency toward taxonomy, that “defines” a species, or even a “family” of living organisms. Take, for example, Linnaeus’ system for dividing plants into types. While his first divisions are clear and understandable, his division of different species of roses gets pretty arbitrary, especially when we consider human-invented species. To answer your question, the causes of one species dying out while closely related species survive can often be traced to loss of environments. Much of that can be blamed on Humanity’s greed, over-consumption, and disregard for the consequences of selfish choices (orangutans in Madagascar, for example, to say nothing of hunting rare species just for sport). In fairness to Humanity, too, we are the only species that is even aware that efforts can be made to preserve species and encourage diversity, or that sees value in doing do. Another cause is natural selection “weeding out” some species, a kind of accordion-like reduction of genetic choices; for example, the Darwinian Galapagos Island bird species have suffered much loss of diversity, simply because some of the species became unviable with time. Finally, environmental changes (whether man-made or not) can deplete species. Take for example the depletion of the polar bear. In short, species survive or not based on many factors, and when those factors change, some species survive and some do not.

Why does Papa Logan have to work on the railroad in Roll of Thunder, Hear My Cry?

Papa has to make extra money to pay for the taxes the Logans owe on their land because the price of cotton dropped due to the Great Depression.

The Logans are farmers.  Even though the Logan family owns land of their own, it is not enough to pay the bills.  The land is valuable, and it is taxed.  The taxes on the land are so high that Papa has to go to find work.  He gets a job working for the railroad to supplement his income.  The crops are not bringing in as much profit as they used to.  This is largely due to the prices the family can get for their crops, which vary from year to year and have been going down.

That was why Papa had gone to work on the railroad.  In 1930 the price of cotton dropped. And so, in the spring of 1931, Papa set out looking for work, going as far north as Memphis and as far south as the Delta country. (Ch. 1)

It is the Great Depression, and everyone is struggling to make ends meet.  Because the price of cotton dropped, working the land is no longer enough to pay the taxes on it and support the family.  If they do not pay the taxes, they will lose the land. 

Because of the need for the railroad job, Papa is often away from home for long stretches at a time.  This leaves the rest of the family alone to have to deal with whatever situation may arise.  Papa is pretty much only there for planting and harvesting the cotton.

Cassie asks her father why he sacrifices so much in order to keep the land.  Her father explains to her the importance of owning land.

“Look out there, Cassie girl. All that belongs to you. You ain’t never had to live on nobody’s place but your own and long as I live and the family survives, you’ll never have to.  That’s important. You may not understand that now, but one day you will. Then you’ll see.” (Ch. 1)

Even though he has to leave his family to make enough money to pay for the land, it is worth it to Papa.  To him, owning land is the thing that is important.  Most of the other families are sharecroppers, which basically means they are renting the land they farm.  To own land is something special, especially when you are an African American family.

What is the significance of the action of the women passing by on the sidewalk in The Secret Life of Walter Mitty?

Walter Mitty is doing some shopping for his wife. He is trying to remember one of the items she told him to get. A passing newsboy is shouting something about a trial in Waterbury and Mitty relapses from the real world, in which he has to do some shopping, into his fantasy world. He becomes a debonaire man of the world on trial for murder. A woman he is trying to protect by taking the blame for her crime throws herself into his arms, and the District Attorney strikes her. 

A woman’s scream rose above the bedlam and suddenly a lovely, dark-haired girl was in Walter Mitty’s arms. Without rising from his chair, Mitty let the man have it on the point of the chin. “You miserable cur!” . . .

“Puppy biscuit,” said Walter Mitty. He stopped walking and the buildings of Waterbury rose up out of the misty courtroom and surrounded him again. A woman who was passing laughed. “He said ‘Puppy biscuit,’ ” she said to her companion. “That man said ‘Puppy biscuit’ to himself.” 

This shows the complexity of Mitty's interrelations with reality and his fantasy life. It also shows the real setting, a street in the shopping district of a large town in Connecticut, in contrast with the fantasy setting of a courtroom in which Mitty himself is on the witness stand. The woman who tells her companion, "He said 'Puppy biscuit'" sounds a little like his wife in that she repeats things just like Mrs. Mitty. The woman tells her companion: "He said 'Puppy biscuit....That man said 'Puppy biscuit' to himself." It is, of course, Mitty's calling the District Attorney "You miserable cur!" in his fantasy that reminds him of the other thing he is supposed to buy. One sentence is particularly striking:

He stopped walking and the buildings of Waterbury rose up out of the misty courtroom and surrounded him again. 

He is probably used to talking to himself. The woman would not have laughed if she had heard him say, for instance, something like, "You miserable cur!" but it seems funny to hear a man say "Puppy biscuit" aloud on the street. It shows how far into his fantasies Walter Mitty was able to go. He may have been a nondescript male walking down the sidewalk, but in his fantasy, which was more real than his monotonous reality, he was a fascinating, fearless man of the world on trial for his life. Evidently Mitty's fantasy of being on trial is partly due to his knowing that his wife is going to grill him about whether he remembered what she wanted him to get.

In a way he hated these weekly trips to town—he was always getting something wrong. Kleenex, he thought, Squibb’s, razor blades? No. Toothpaste, toothbrush, bicarbonate, carborundum, initiative and referendum? He gave it up. But she would remember it. “Where’s the what’s-its-name?” she would ask. “Don’t tell me you forgot the what’s-its-name.” 

The words "Puppy biscuit" also show that the Mittys have a puppy at home. Thurber was a dog-lover. His drawings of dogs were seen in editions of The New Yorker for many years. They were so familiar to New Yorker readers that they seemed almost symbolic of the spirit of the magazine. The kind of dog he usually drew was a big dog with long ears, possibly a hunting dog like a retriever. The dog always looks sad and befuddled in Thurber's drawings, and he seems to reflect Thurber's own personality and world view. Everybody who read The New Yorker understood that in writing about the secret life of Walter Mitty, James Thurber was really writing about the secret life of James Thurber. He frequently wrote humorous stories and sketches in which he confessed being out of step with the rest of the world. He was undoubtedly influenced to some extent by the Canadian humorist Stephen Leacock. 

What are the effects of medical marijuana?

While a bit vague, the effects of medical marijuana on the body are the same as those of regular marijuana. These effects are caused by a chemical compound known as delta-9-tetrahydrocannabinol, or more simply THC. THC belongs to a class of compounds known as cannabinoids. The human body can also naturally produce its own cannabinoids that are different, but chemically closely related, to THC. These cannabinoids act on specific receptors, known as cannabinoid receptors, located...

While a bit vague, the effects of medical marijuana on the body are the same as those of regular marijuana. These effects are caused by a chemical compound known as delta-9-tetrahydrocannabinol, or more simply THC. THC belongs to a class of compounds known as cannabinoids. The human body can also naturally produce its own cannabinoids that are different, but chemically closely related, to THC. These cannabinoids act on specific receptors, known as cannabinoid receptors, located in the brain and throughout the body. Another cannabinoid, cannabidiol, also known as CBD,  is also found in marijuana and can activate cannabinoid receptors, without producing the same "high" feeling as THC.

Activation of these receptors leads to a number of effects in the body and mind. Short term effects of both regular and medical marijuana generally include, change in the persons mood, changes in the persons sense of time, often times making them feel as if time is passing more slowly, altered senses, and an increased appetite. Accompanying these effects are, in most users, feelings of happiness and relaxation.  

In the body, activation of these receptors, by cannabinoids found in marijuana, can be used to help in a number of treatments for various diseases. One such thing these compounds can do is increase appetite, and also decrease nausea, in patients undergoing radiation chemotherapy. This helps the patient to ease their suffering, and allows them to be able to eat more successfully while undergoing treatment. Studies in mice have also shown that activation of cannabinoid receptors may be able to help slow the progression of cancer tumor cells, and possibly increase the ability of chemotherapy to kill cancer cells, although further studies need to be conducted to evaluate this claim. Activation of cannabinoids can also lead to a state of relaxation. Because of this, medical marijuana can also be used as a treatment for disorders that involve controlling such things as inflammation and pain in the body. Hope this helps!

Explore the ways Shakespeare presents good and bad in the character Macbeth.

Over the course of the play, we witness Macbeth's rapid descent into almost pure evil. Shakespeare presents Macbeth at the beginning of the play as a good man, a "worthy kinsman" according to his cousin, King Duncan. Macbeth is "good" (or at least Duncan thinks he is) because he is loyal to the King and steadfast in carrying out his duty as a thane to Duncan. He is contrasted with the wicked rebel Macdonwald, who...

Over the course of the play, we witness Macbeth's rapid descent into almost pure evil. Shakespeare presents Macbeth at the beginning of the play as a good man, a "worthy kinsman" according to his cousin, King Duncan. Macbeth is "good" (or at least Duncan thinks he is) because he is loyal to the King and steadfast in carrying out his duty as a thane to Duncan. He is contrasted with the wicked rebel Macdonwald, who he is described as having killed in battle, and the thane of Cawdor, who is executed as a result of his treachery. 

Just before he kills Duncan, we see at least some good in Macbeth. He hesitates before the murder on the grounds that there is nothing but "vaulting ambition" that drives him to do the deed. He realizes that the murder is especially evil because Duncan is his kinsman, his king, and because he is honor-bound to provide the man with hospitality in his castle. So violating these ties is portrayed as evil. Macbeth has both violated his obligations to his lord and relative and attempted to transcend his place in society by usurping the crown. By the end of the play, Macbeth has become a figure of almost unmitigated evil, having Banquo and Macduff's family murdered in an attempt to keep his crown.

How does body weight affect respiratory rate during exercise?

Carrying around excess body weight puts a great deal of strain on the entire body, including the respiratory system. People who are overweight have to work harder to do the same exact things that a person in the healthy weight range has to do. The more strenuously we exercise the more oxygen and nutrients need to be delivered to our bodies. The larger the body, the more oxygen and nutrients we need. As we continue...

Carrying around excess body weight puts a great deal of strain on the entire body, including the respiratory system. People who are overweight have to work harder to do the same exact things that a person in the healthy weight range has to do. The more strenuously we exercise the more oxygen and nutrients need to be delivered to our bodies. The larger the body, the more oxygen and nutrients we need. As we continue to exercise our respirations become even faster in order to deliver what we need to survive. In addition, depending on how heavy a person is, extra weight can put pressure on the area around our lungs and heart which can cause additional labored breathing, increasing our rate of respiration even more. 

How does Atticus's decision to be Tom Robinson's defense lawyer impact Scout and Jem in Harper Lee's To Kill a Mockingbird?

In Harper Lee's To Kill a Mockingbird, one way in which Scout and Jem are impacted by their father's decision to be Tom Robinson's defense lawyer is that they must suffer ridicule from Maycomb's townspeople.

Scout is the first to be ridiculed as a result of their father's decision when Cecil Jacobs, her schoolmate, declares in the schoolyard that "Scout Finch's daddy defended niggers" (Ch. 9). Scout is not really sure what Cecil means in saying so, but she knows she feels insulted and is ready to fight Cecil, breaking her promise to her father not to fight anymore.

Jem takes the hardest blow of ridicule from Mrs. Henry Lafayette Dubose, the reputed meanest old lady in the neighborhood. By Chapter 11, Jem and Scout feel old enough to force themselves to walk past Mrs. Dubose's house in order to get to town, whereas prior, they had avoided her house like the plague. Each time they walk past her house, no matter how genteel they feel they are being towards her, she hurls insults at the children. Mrs. Dubose hurls what Jem considers to be her worst insult when she verbally attacks their father after having predicted Scout would grow up to wait on tables at a dive because she does not act like a lady:

Not only a Finch waiting on tables but one in the courthouse lawing for niggers! ... Yes indeed, what has this world come to when a Finch goes against his raising? I'll tell you! ... Your father's no better than the niggers and trash he works for! (Ch. 11)

Mrs. Dubose's remarks infuriate Jem so much that he destroys her flower garden.

The townspeople's ridicule leaves Scout feeling confused because she thinks that if the whole town thinks Atticus is wrong to defend Tom Robinson, then surely Atticus must be wrong, as she expresses to her father one day:

Atticus, you must be wrong ... Well, most folks seem to think they're right and you're wrong ... (Ch. 11)

Yet, despite the ridicule, Atticus remains firm in his conviction that it is his moral imperative to defend a man when no concrete evidence exists to prove his guilt. Through it all, the children learn valuable lessons about courage and about mankind's evil, prejudiced nature.