So, this is for anybody who is taking the AP biology test! I made it to help me study...I've been told that "interacting" with my text will help me learn it better. I might post some more later. They're not exactly the most entertaining thing I've ever written, but hopefully they'll help somebody :)

"Let's stay here all day," Blaine mumbled into the side of the pillow. "Let's never, ever, ever move again."

He heard Kurt's laugh from the other side of the room.

"Come on," he felt Kurt's hands on the small of his back, tugging at his shirt. "I've got to study…so do you." He groaned as Kurt pulled him into a sitting position. It was way too early for studying.

"What's the subject?"

Kurt flashed him a grin, "cellular respiration."

"Sexy."

"Okay," Kurt slammed the book down on the table. "So, let's start where it all starts—glycolysis."

"You are way too excited about this."

"Come on; just pretend like it's fun." Blaine rolled his eyes.

"Anyway," Kurt continued. "You start with a glucose molecule and—"

"Now I want candy." Blaine widened his eyes a little and gave Kurt the puppy-dog stare. Kurt let out a frustrated sigh.

"One piece," Blaine wedeled. "I promise I'll be good."

Kurt got up and went to the cupboard. He tossed Blaine a Hershey's kiss and gave a reluctant smile as Blaine's face lit up.

"Happy?"

"Oh, so happy," Blaine agreed, opening his mouth to show Kurt. Kurt made a face and sat back down next to Blaine. "Explain it to me," Blaine said, the words coming out a little mumbled since his tongue was still maneuvering around the chocolate.

"Fine," Kurt let out a sigh. "So, you're eating the piece of chocolate. The glucose in the chocolate is going to be broken down. Since you're breathing, and you have ample oxygen, it will be aerobic respiration."

"And if I was yeast in a vat with no oxygen?"

"Anaerobic; you could either do alcoholic fermentation or lactic acid fermentation."

"Ha-ha, Kurt!" Blaine's eyes spring to life. "Does that mean that if we held our breath and ran in circles we could get drunk off of our sugar turning into alcohol?"

"No," Kurt couldn't help smiling. "We don't have the genes to do that. We do lactic acid fermentation, which is why if you were to hold your breath and run around in circles you would get a cramp."

Blaine's face fell a little bit. "Oh."

"Besides," Kurt pressed a kiss to the shell of Blaine's ear. "It's all for the best; you tend to get a little…hands on when you're drunk."

"It still would be cool," Blaine mumbled.

"To bad you're not a yeast."

"So what happens next?"

"Well, the glucose goes through glycolysis where it is broken down into two pyruvate molecules, four CO2 molecules, 4 ATP molecules and 2 NADH molecules. However, since it takes two ATP to go through glycolysis, you really only netted two ATP molecules."

"After glycolysis, you need to break down the pyruvate even more. The pyruvate gets broken down into 2 acetyl CoA molecules as well as two NADH molecules. The acetyl CoA can now go through the Krebs cycle. Basically, each acetyl CoA gets broken down into 1 ATP, 2 CO2, 1 FADH2, and 3 NADH, which means that when the cycle has run through both times, it will have produced 2 ATP, 4 CO2, 2 FADH2, and 6 NADH."

"My boyfriend is a smarty," Blaine said, resting his head on Kurt's shoulder.

"I'm not done yet," Kurt hushed him.

"Sorry," Blaine said, nuzzling into Kurt's neck. "Continue."

"So after you've gone through the Krebs cycle, the FADH2 and NADH go through the ETC, or electron transport chain. There, NADH is dumped on FMN and releases 3 ATP per NADH molecule. FADH2 is dumped on ubiquinone, which is at a lower energy state, and therefore only yields 2 ATP per molecule."

"Where is this all happening?" Blaine asked, slowly planting kisses up along Kurt's jawline.

"Your mitochondria," Kurt said, squirming away from the kisses. "The Krebs cycle takes place in the matrix and the ETC and ATP synthase are on the inner membrane."

"Say that again," Blaine said, a smile tugging at his lips.

"What?"

"Inner membrane."

"Why?"

"You sound sexy when you say it."

Kurt let out a groan. "Blaine, you are an impossible study buddy."

"Yeah," Blaine sighed. "I'm a good bed-buddy, though."

"Oh my god," Kurt dissolved into a fit of laughter.

"Come on, let's finish up," Blaine gave Kurt's shoulders a light shake.

"Right, okay, sorry," Kurt cleared his throat. "So then we go back to anaerobic respiration—lactic acid fermentation and alcoholic fermentation."

"Which I am unable to do," Blaine noted.

"Right," Kurt smiled. "So in alcoholic fermentation, you make two ethanol molecules, two CO2, and 2 NAD+. That's why it's important to do alcoholic fermentation—you have to convert the NADH back into NAD+. It needs to do this so that glycolysis can continue and produce more ATP."

"Mmm," Blaine mumbled.

"I'm almost done," Kurt promised. "Lactic acid fermentation produces two lactate and two NAD+, again it's important for this to happen because the NADH needs to be replenished/returned to NAD+ so that glycolysis can produce ATP."

"Kurt?" Blaine raised his head up a little, squinting lazily at the side of Kurt's face. "You said that the difference between anaerobic and aerobic respiration was that there was oxygen in aerobic and that there wasn't in anaerobic. So what exactly does the oxygen do?"

"Good question," Kurt beamed, leaning down to plant a kiss on Blaine's forehead. "Oxygen accepts the electrons at the end of the electron transport chain."

"Is kissing aerobic or anaerobic?"

Kurt opened his mouth and then closed it again, tilting his head to the side.

"Well…I was going to say aerobic but then again, you can't breathe through your mouth…"

"Your nose?"

"Yeah, I guess."

"Kurt?"

"Yeah?"

"Study break?"

"What did you have in mind?"

"Aerobic respiration?"