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Look carefully at the picture below and answer the questions.

1. How many tourists are staying at this camp?
2. When did they arrive: today or a few days ago?
3. How did they get here?
4. How far away is the closest village?
5. Where does the wind blow: from the north or from the south?
6. What time of day is it?
7. Where did Alex go?
8. Who was on duty yesterday? (Give their name)
9. What day is it today?

1. There are 4 people.
2. They arrived a few days ago, enough so that a spider web can appear on the tent.
3. Judging by the paddles, they got there with boats.
4. There is a hen walking around the camp, so the closest village is not far away.
5. The leaves of the trees are larger at the south side, so the wind must be blowing from the South.
6. The shadow is pointing towards West, so it must be morning.
7. Alex went to catch butterflies.
8. Since Peter is on duty today – cooking food for the group, it was Colin on duty yesterday.
9. Today is August 8. Watermelons ripen in August.

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Who says science jokes are not funny? Below you can see some of the best Biology jokes we know, along with short explanations of the more obscure of them.

Do you know any funny Biology jokes yourself? Let us know in the comment section below.


Two blood cells met and fell in love. Alas, it was all in vein.

Explanation
A clever wordplay with the words “vein” and “vain”.


Pavlov is sitting at a pub, enjoying a pint. Suddenly the phone rings and he jumps up shouting, “Oh no, I forgot to feed the dog!”

Explanation
Pavlov is a physiologist who used to ring a bell every time he fed his dogs. After some time, he noticed that ringing the bell by its own caused salivation in his dogs, even if he didn’t offer them any food.


“I wish I was adenine, then I could get paired with U.”

Explanation
In RNA (Ribonucleic acid), adenine (A) makes a “base pair” with uracil (U).


“What did one sister chromatid say to the other?”
“Stop copying me.”

Explanation
“Sister chromatids” are two identical chromatids (replicated chromosomes), which are joined with each other.


What does DNA stand for? National Dyslexia Association.

Explanation
Dyslexia is a reading disorder, which causes various troubles during reading, even for people with normal intelligence. If read correctly, the abbreviation for National Dyslexia Association should be NDA, not DNA.


“What did the stimulus do to the neuron after they got married?”
“It carried it over the threshold.”

Explanation
The “threshold” is the depolarization level over which a stimulus must carry the neuron, in order for an action potential to be fired.


An infectious disease enters a bar. The bartender says, “We don’t serve your kind here”. The disease replies, “Well, you are not a very good host.”

Explanation
The word “host” has several meanings, one of which is “a person who accommodates guests”, and another one is “an animal or a plant in which a parasite lives”.


The scientists have just found the gene for shyness. They would have found it earlier, but it was hiding behind two other genes.


“What is the fastest way to determine the sex of a chromosome?”
“Pull down its genes.”

Explanation
Word play with the words “genes” and “jeans”.


One lab rat says to another:
I’ve got my scientist so well trained that every time I push the buzzer, he brings me a snack.”


“Girl, you are so hot, you denature my proteins.”

Explanation
When things get hot, proteins denature, i.e. lose their shape and structure.


“What did Gregor Mendel say when he founded genetics?”
“Woopea!”

Explanation
Gregor Mendel made his experiments using pea plants.


“What is sleeping brain’s favorite rock band?”
“REM”

Explanation
REM stands for “rapid eye movement”, which occurs during sleep.

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After you die, you somehow appear in a mystical room, which has two doors in it. In front of each door, there is a keeper – one of them always lying, the other one always telling the truth. If you enter the door of the lying keeper, you go straight to Hell. If you enter the door of the truthful keeper, you go straight to Heaven. You can ask one of the keepers whatever question you want (you don’t know which keeper is lying and which is truthful). What should you ask in order to go to Heaven?

You can point your finger to one of the two rooms and ask any of the keepers the question “If I ask the other keeper whether this room leads to Heaven, would he say YES?”. If the answer is NO, go through that door, if the answer is YES, go through the other one.

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Show that in each group of 6 people, there are either 3 which know each other, or 3 which do not know each other.

Let’s call the people A, B, C, D, E, F. Person A either knows at least 3 among B, C, D, E, F, or does not know at least 3 among B, C, D, E, F.

Assume the first possibility – A knows B, C, D. If B and C know each other, C and D know each other, or B and D know each other, then we find a group of 3 people which know each other. Otherwise, B, C and D form a group in which noone knows the others.

If A doesn’t know at least 3 among B, C, D, E, F, the arguments are the same.

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If you have 10 dots on a table, can you always cover them with 10 pennies without overlapping?

Remark: You can assume the dots are not too close to the edge of the table.

SOLUTION

Assume the dots lie in a plane and the radius of a penny is 1. Make an infinite grid of circles with radii 1, as shown on the picture, and place it randomly in the plane.

If we choose any point in the plane, the probability that it will end up inside some circle of the grid is equal to S(C)/S(H), where S stands for “area”. A simple calculation shows that this ratio is bigger than 90%. Therefore the probability that some chosen point in the plane will not end up inside any circle is less than 10%. If we have 10 points, the probability that neither of them will end up inside a circle is less than 100%. Therefore we can place the grid in the plane so that all dots end up in some circles. Now just place the given coins where these circles are.

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At some point in Leonel Messi’s career, the football player had less than 80% success when performing penalty kicks. Later in his career, he had more than 80% success when performing penalty kicks. Show that there was a moment in Leonel Messi’s career when he had exactly 80% success when performing penalty kicks.

SOLUTION

Let us see that it is impossible for Messi to jump from under 80% success rate to over 80% success rate in just one attempt. Indeed, if Messi’s success rate was below 80% after N attempts, then he scored at most 4N/5 – 1/5 = (4N-1)/5 times. If his success rate was above 80% after N+1 attempts, then he scored at least 4(N+1)/5 + 1/5 = (4N-1)/5 + 6/5 times. However, Messi can not score more than one goal in a single attempt, which completes the proof.