TedTest

From the Ted Talk by Aaron Reedy: Sex determination More complicated than you thought

Unscramble the Blue Letters

My wife is pregnant right now with our first child, and when people see her with her big baby bump, the first question people ask, almost without fail, is, "Is it a boy or is it a girl?" Now, there are some assumptions behind that question that we take for granted because of our firtaailimy with our own human biology. For haumn babies, we take it for granted that there's a 50/50 chance of either answer, boy or girl. But why is it that way? Well, the answer depends on the sex determination steysm that has eeolvvd for our sepceis. You see, for most mammals, the sex of a baby is determined gnltilecaey with the XY chromosome system. Mammals have a pair of sex chromosomes, one psesad down from mom, and one from dad. A pair of X's gives us a girl, and an X and a Y together gives us a boy. Since females only have X's to pass on in their egg cells, and males can give either an X or a Y in their sperm cells, the sex is determined by the fhetar and the chance of producing a male or a female is 50/50. This system has wrekod well for mammals, but throughout the tree of life, we can see other systems that have worked just as well for other animals. There are other gorups of animals that also have genetic sex determination, but their smtsyes can be pretty different from ours. Birds and some riptlees have their sex genetically determined, but instead of the sex being determined by dad, their sex is determined by mom. In those groups, a pair of Z sex chromosomes produces a male, so these males only have Z's to give. However, in these animals, one Z and one W chromosome together, as a pair, produces a female. In this system, the cnache of a male or a female is still 50/50, it just depends on whether mom puts a Z or a W into her egg. Certain groups have taken genetic sex determination in cellmtoepy other directions. Ants, for example, have one of the most interesting systems for determining sex, and because of it, if you are a male ant, you do not have a father. In an ant colony, there are dramatic dinvsiios of labor. There are soldiers that defend the colony, there are workers that collect food, clean the nest and care for the young, and there's a queen and a small group of male reproductives. Now, the queen will mate and then store serpm from the mleas. And this is where the system gets really interesting. If the queen uses the stored sperm to fertilize an egg, then that egg will grow up to become female. However, if she lays an egg without fertilizing it, then that egg will still grow up to be an ant, but it will always be a male. So you see, it's impossible for male ants to have fathers. And male ants live their life like this, with only one copy of every gene, much like a walking sex cell. This system is called a hpilaopioldd system, and we see it not only in ants, but also in other highly social insects like bees and wsaps. Since our own sex is determined by genes, and we do know of these other ainlams that have their sex determined by genes, it's easy to ausmse that for all animals the sex of their babies still must be dteniremed by genetics. However, for some animals, the question of whether it will be a boy or a girl has nothing to do with genes at all, and it can depend on something like the weather. These are animals like alligators and most turtles. In these animals, the sex of an embryo in a developing egg is determined by the temperature. In these species, the sex of the baby is not yet determined when the egg is laid, and it rineams undetermined until sometime in the mildde of the overall development period, when a critical time is reached. And during this time, the sex is completely determined by tptrearueme in the nest. In painted turtles, for example, warm temperatures above the critical temperature will pocrdue females within the eggs, and cool temperatures will produce a male. I'm not sure who came up with this mnemonic, but you can remember that when it comes to pneitad turtles, they are all hot chicks and cool dudes. For some tropical fish, the question of will it be a boy or will it be a girl isn't settled until even later in life. You see, clownfish all start out their lives as males, However, as they murtae, they become female. They also spend their lives in samll groups with a strict dominance hierarchy where only the most dnmaoint male and female reproduce. And amazingly, if the dominant female in the gruop dies, the lgaerst and most dominant male will then quickly become female and take her palce, and all of the other males will move up one rank in the hircrhaey. In another very different ocean aianml, the geren spoonworm, the sex of the babies is determined by a completely different acepst of the environment. For this species, it is silmpy a matter of where a larva happens to randomly fall on the sea floor. If a lvara lands on the open sea floor, then it will become a female. But if it ldnas on top of a female, then it will become a male. So for some species, the question of boy or girl is answered by genetics. For others, it's asnreewd by the environment. And for others still, they don't even btoehr with the qeuositn at all. Take wtihapil lizards, for example. For those desert lizards, the answer is easy. It's a girl. It's always a girl. They are a nearly all-female species, and although they still lay eggs, these eggs hatch out flamee clones of themselves. So will it be a girl or will it be a boy? Throughout the entire animal knogdim, it does really all denped on the system of sex determination. For hnuams, that system is a genetic XY system. And for me and my wife, we found out it's going to be a baby boy. (Kiss)

Open Cloze

My wife is pregnant right now with our first child, and when people see her with her big baby bump, the first question people ask, almost without fail, is, "Is it a boy or is it a girl?" Now, there are some assumptions behind that question that we take for granted because of our ___________ with our own human biology. For _____ babies, we take it for granted that there's a 50/50 chance of either answer, boy or girl. But why is it that way? Well, the answer depends on the sex determination ______ that has _______ for our _______. You see, for most mammals, the sex of a baby is determined ___________ with the XY chromosome system. Mammals have a pair of sex chromosomes, one ______ down from mom, and one from dad. A pair of X's gives us a girl, and an X and a Y together gives us a boy. Since females only have X's to pass on in their egg cells, and males can give either an X or a Y in their sperm cells, the sex is determined by the ______ and the chance of producing a male or a female is 50/50. This system has ______ well for mammals, but throughout the tree of life, we can see other systems that have worked just as well for other animals. There are other ______ of animals that also have genetic sex determination, but their _______ can be pretty different from ours. Birds and some ________ have their sex genetically determined, but instead of the sex being determined by dad, their sex is determined by mom. In those groups, a pair of Z sex chromosomes produces a male, so these males only have Z's to give. However, in these animals, one Z and one W chromosome together, as a pair, produces a female. In this system, the ______ of a male or a female is still 50/50, it just depends on whether mom puts a Z or a W into her egg. Certain groups have taken genetic sex determination in __________ other directions. Ants, for example, have one of the most interesting systems for determining sex, and because of it, if you are a male ant, you do not have a father. In an ant colony, there are dramatic _________ of labor. There are soldiers that defend the colony, there are workers that collect food, clean the nest and care for the young, and there's a queen and a small group of male reproductives. Now, the queen will mate and then store _____ from the _____. And this is where the system gets really interesting. If the queen uses the stored sperm to fertilize an egg, then that egg will grow up to become female. However, if she lays an egg without fertilizing it, then that egg will still grow up to be an ant, but it will always be a male. So you see, it's impossible for male ants to have fathers. And male ants live their life like this, with only one copy of every gene, much like a walking sex cell. This system is called a ____________ system, and we see it not only in ants, but also in other highly social insects like bees and _____. Since our own sex is determined by genes, and we do know of these other _______ that have their sex determined by genes, it's easy to ______ that for all animals the sex of their babies still must be __________ by genetics. However, for some animals, the question of whether it will be a boy or a girl has nothing to do with genes at all, and it can depend on something like the weather. These are animals like alligators and most turtles. In these animals, the sex of an embryo in a developing egg is determined by the temperature. In these species, the sex of the baby is not yet determined when the egg is laid, and it _______ undetermined until sometime in the ______ of the overall development period, when a critical time is reached. And during this time, the sex is completely determined by ___________ in the nest. In painted turtles, for example, warm temperatures above the critical temperature will _______ females within the eggs, and cool temperatures will produce a male. I'm not sure who came up with this mnemonic, but you can remember that when it comes to _______ turtles, they are all hot chicks and cool dudes. For some tropical fish, the question of will it be a boy or will it be a girl isn't settled until even later in life. You see, clownfish all start out their lives as males, However, as they ______, they become female. They also spend their lives in _____ groups with a strict dominance hierarchy where only the most ________ male and female reproduce. And amazingly, if the dominant female in the _____ dies, the _______ and most dominant male will then quickly become female and take her _____, and all of the other males will move up one rank in the _________. In another very different ocean ______, the _____ spoonworm, the sex of the babies is determined by a completely different ______ of the environment. For this species, it is ______ a matter of where a larva happens to randomly fall on the sea floor. If a _____ lands on the open sea floor, then it will become a female. But if it _____ on top of a female, then it will become a male. So for some species, the question of boy or girl is answered by genetics. For others, it's ________ by the environment. And for others still, they don't even ______ with the ________ at all. Take ________ lizards, for example. For those desert lizards, the answer is easy. It's a girl. It's always a girl. They are a nearly all-female species, and although they still lay eggs, these eggs hatch out ______ clones of themselves. So will it be a girl or will it be a boy? Throughout the entire animal _______, it does really all ______ on the system of sex determination. For ______, that system is a genetic XY system. And for me and my wife, we found out it's going to be a baby boy. (Kiss)

Solution

humans
small
question
worked
groups
genetically
animals
bother
mature
remains
largest
temperature
wasps
system
assume
haplodiploid
father
familiarity
middle
kingdom
systems
human
place
group
lands
evolved
determined
female
painted
completely
aspect
passed
reptiles
animal
green
dominant
simply
produce
larva
depend
hierarchy
chance
divisions
sperm
males
whiptail
answered
species

Original Text

My wife is pregnant right now with our first child, and when people see her with her big baby bump, the first question people ask, almost without fail, is, "Is it a boy or is it a girl?" Now, there are some assumptions behind that question that we take for granted because of our familiarity with our own human biology. For human babies, we take it for granted that there's a 50/50 chance of either answer, boy or girl. But why is it that way? Well, the answer depends on the sex determination system that has evolved for our species. You see, for most mammals, the sex of a baby is determined genetically with the XY chromosome system. Mammals have a pair of sex chromosomes, one passed down from mom, and one from dad. A pair of X's gives us a girl, and an X and a Y together gives us a boy. Since females only have X's to pass on in their egg cells, and males can give either an X or a Y in their sperm cells, the sex is determined by the father and the chance of producing a male or a female is 50/50. This system has worked well for mammals, but throughout the tree of life, we can see other systems that have worked just as well for other animals. There are other groups of animals that also have genetic sex determination, but their systems can be pretty different from ours. Birds and some reptiles have their sex genetically determined, but instead of the sex being determined by dad, their sex is determined by mom. In those groups, a pair of Z sex chromosomes produces a male, so these males only have Z's to give. However, in these animals, one Z and one W chromosome together, as a pair, produces a female. In this system, the chance of a male or a female is still 50/50, it just depends on whether mom puts a Z or a W into her egg. Certain groups have taken genetic sex determination in completely other directions. Ants, for example, have one of the most interesting systems for determining sex, and because of it, if you are a male ant, you do not have a father. In an ant colony, there are dramatic divisions of labor. There are soldiers that defend the colony, there are workers that collect food, clean the nest and care for the young, and there's a queen and a small group of male reproductives. Now, the queen will mate and then store sperm from the males. And this is where the system gets really interesting. If the queen uses the stored sperm to fertilize an egg, then that egg will grow up to become female. However, if she lays an egg without fertilizing it, then that egg will still grow up to be an ant, but it will always be a male. So you see, it's impossible for male ants to have fathers. And male ants live their life like this, with only one copy of every gene, much like a walking sex cell. This system is called a haplodiploid system, and we see it not only in ants, but also in other highly social insects like bees and wasps. Since our own sex is determined by genes, and we do know of these other animals that have their sex determined by genes, it's easy to assume that for all animals the sex of their babies still must be determined by genetics. However, for some animals, the question of whether it will be a boy or a girl has nothing to do with genes at all, and it can depend on something like the weather. These are animals like alligators and most turtles. In these animals, the sex of an embryo in a developing egg is determined by the temperature. In these species, the sex of the baby is not yet determined when the egg is laid, and it remains undetermined until sometime in the middle of the overall development period, when a critical time is reached. And during this time, the sex is completely determined by temperature in the nest. In painted turtles, for example, warm temperatures above the critical temperature will produce females within the eggs, and cool temperatures will produce a male. I'm not sure who came up with this mnemonic, but you can remember that when it comes to painted turtles, they are all hot chicks and cool dudes. For some tropical fish, the question of will it be a boy or will it be a girl isn't settled until even later in life. You see, clownfish all start out their lives as males, However, as they mature, they become female. They also spend their lives in small groups with a strict dominance hierarchy where only the most dominant male and female reproduce. And amazingly, if the dominant female in the group dies, the largest and most dominant male will then quickly become female and take her place, and all of the other males will move up one rank in the hierarchy. In another very different ocean animal, the green spoonworm, the sex of the babies is determined by a completely different aspect of the environment. For this species, it is simply a matter of where a larva happens to randomly fall on the sea floor. If a larva lands on the open sea floor, then it will become a female. But if it lands on top of a female, then it will become a male. So for some species, the question of boy or girl is answered by genetics. For others, it's answered by the environment. And for others still, they don't even bother with the question at all. Take whiptail lizards, for example. For those desert lizards, the answer is easy. It's a girl. It's always a girl. They are a nearly all-female species, and although they still lay eggs, these eggs hatch out female clones of themselves. So will it be a girl or will it be a boy? Throughout the entire animal kingdom, it does really all depend on the system of sex determination. For humans, that system is a genetic XY system. And for me and my wife, we found out it's going to be a baby boy. (Kiss)

Frequently Occurring Word Combinations

ngrams of length 2

collocation	frequency
sex determination	3
genetic sex	2
male ants	2
dominant male	2

Important Words

alligators
amazingly
animal
animals
answer
answered
ant
ants
aspect
assume
assumptions
babies
baby
bees
big
biology
birds
bother
boy
bump
called
care
cell
cells
chance
chicks
child
chromosome
chromosomes
clean
clones
clownfish
collect
colony
completely
cool
copy
critical
dad
defend
depend
depends
desert
determination
determined
determining
developing
development
dies
directions
divisions
dominance
dominant
dramatic
dudes
easy
egg
eggs
embryo
entire
environment
evolved
fail
fall
familiarity
father
fathers
female
females
fertilize
fertilizing
fish
floor
food
gene
genes
genetic
genetically
genetics
girl
give
granted
green
group
groups
grow
haplodiploid
hatch
hierarchy
highly
hot
human
humans
impossible
insects
interesting
kingdom
kiss
labor
laid
lands
largest
larva
lay
lays
life
live
lives
lizards
male
males
mammals
mate
matter
mature
middle
mnemonic
mom
move
nest
ocean
open
painted
pair
pass
passed
people
period
place
pregnant
pretty
produce
produces
producing
puts
queen
question
quickly
randomly
rank
reached
remains
remember
reproduce
reproductives
reptiles
sea
settled
sex
simply
small
social
soldiers
species
spend
sperm
spoonworm
start
store
stored
strict
system
systems
temperature
temperatures
time
top
tree
tropical
turtles
undetermined
walking
warm
wasps
weather
whiptail
wife
worked
workers
xy
young