"Harry Potter and the Half-Blood Prince" Part I Quiz

Answer: in a subway (tube) station

We first see Harry in a cafe in a subway (or underground) station. He is reading a paper and flirting with the waitress. Something causes him to look up and, after a subway train passes, he sees Dumbledore standing on the other side of the tracks. Harry uses the stairs to reach Dumbledore, who takes Harry with him, to help him with an important chore.
This is very different from the book where Dumbledore calls at the Dursleys' house to collect Harry. The fact that Harry is wandering around alone at night, when witches and wizards are disappearing at an alarming rate, is something that would not have been allowed in the book. However in the movie, the only concession made to this risk is when Dumbledore tells Harry that he's been careless over the summer.
Michael Gambon plays Dumbledore and Daniel Radcliffe plays Harry Potter.

Answer: The blood dripping from the ceiling is dragon's blood.

When they first approach the house and he sees the condition that it's in, Dumbledore tells Harry to get his wand out. Once inside, they find that the extent of the wreckage is extensive and there is a large patch of blood dripping down from the ceiling.

A drop falls on Harry's face and Dumbledore tastes it. He then points his wand at the chair which turns out to be a disguised Slughorn. Slughorn explains that he has said no to the Death Eaters a few times and is worried about repercussions. He then asks Dumbledore what gave him away and Dumbledore says "Dragon's blood." Slughorn is played by Jim Broadbent.

Answer: Wormtail

When the two women first knock on the door, it is Wormtail who answers it. Snape then dismisses him before engaging in a conversation with the women, using his wand to cause the door to slam in Wormtail's face. As this is the only time he is seen in the entire movie, one wonders why they bothered including him.
Wormtail's real name is Peter Pettigrew, and he is the Death Eater who revealed the Potter's location to Voldemort, on the night that James and Lily were killed. He faked his own death (causing Sirius to be imprisoned for it) and spent years hiding out as the Weasley's pet rat.
Lucius Malfoy, we learn from the headlines in the paper that Harry was reading, is a prisoner in Azkaban.
Wormtail is played by Timothy Spall.

Answer: the Unbreakable Vow

Narcissa is distraught about the task that Voldemort has set for her son, Draco, and wants Snape to promise to help him. Her sister, Bellatrix, does not trust Snape and says that without the Unbreakable Vow, his promises are meaningless. Snape surprises her by telling her to take out her wand and she officiates over the Unbreakable Vow between Snape and Narcissus. He promises to protect and help Draco to the best of his abilities, and to finish Draco's task if he Draco unable to do so.
Snape is played by Alan Rickman, Bellatrix by Helena Bonham Carter and Narcissa by Helen McCrory.

Answer: Luna Lovegood

Harry is suspicious of Malfoy's actions, with good reason. So he hides himself under his invisibility cloak, on the shelf above where Draco is sitting on the train, to listen to what he says. Malfoy sees a bag move and realizes that something is up. After everyone leaves the car, he fires a spell at the rack, petrifying Harry, who falls to the floor. After kicking Harry in the face (for his father) Draco leaves him, petrified and invisible, and heads out the door.
Luna comes through wearing her special glasses to help her see Wrackspurts, which she had discussed in an earlier scene. She sees a bunch flying around Harry's concealed head. Her spell releases Harry and they walk to Hogwarts together. Always seen as being a bit ditzy, this scene leaves us wondering if Luna isn't right about other things that she has been laughed at for believing.
Draco is played by Tom Felton and Luna is played by Evanna Lynch.

Answer: Severus Snape

There has been a different DADA teacher every year that our friends have been at Hogwarts, and through it all, it has been made clear that that was the assignment that Snape really wanted, instead of Potions. This year, with Dumbledore coaxing his old friend Horace Slughorn back into his old position of Potions Master, Snape is finally given a shot at teaching what he really wants to teach.

However we do not see a scene with Snape actually teaching Harry and his friends.

Answer: Half-Blood Prince

As Harry leafs through the book he finds an inscription that says that the book is the property of 'the Half-Blood Prince'. There is much speculation as to who this could be, with Hermione searching through the library, with no success. At the very end of the movie we learn that Snape is the Half-Blood Prince.

In the book we find that, with only one magical parent, Snape is a half-blood, and his mother's surname was Prince.

Answer: He brews a perfect draught and wins the Felix Felicis.

The differences between the instructions in the book and the Prince's suggestions are subtle, but they make a huge difference. Instead of cutting a very tough pod to obtain its juices, as instructed, Harry flattens it with the side of the blade. Instead of adding 12 of a certain kind of seed, he adds 13 as the Prince suggests.
Harry's success with the Draught of Living Death causes him to become fascinated with the book and he spends hours pouring over it. He also becomes Slughorn's star Potion's student, much to Hermione's disgust (because it is not earned honestly) and jealousy.

Answer: of the day Dumbledore visited Tom Riddle in the orphanage

The reason Tom Riddle was left in an orphanage is explained in the book, although not dealt with in the movie. When he became old enough to attend Hogwarts, Dumbledore (then still just a professor) visited the orphanage to introduce himself to Riddle and to make some sort of explanation to the staff. The memory, that he shared with Harry through the Pensieve, shows a young man who already has some awareness of his own powers, and who is already 'punishing' those who hurt him in some way.
In the book, there are many other memories that Dumbledore shares with Harry than are shown in the movie, including ones surrounding the suspicious acquisition of both the ring and the locket used for horcruxes.
Hero Fiennes-Tiffin plays the young Riddle.

Answer: He is not seen in this film.

The adult Lord Voldemort does not make an appearance in this film, although his presence is very much felt through the actions of his Death Eaters. The kidnapping of Ollivander is done by Death Eaters and the significance of this is not discussed until "The Deathly Hallows". The bridge destroyed in the film is the London Millennium Bridge.