Getting your questions ready
Getting your questions ready
All 10 questions with answers and explanations. Play this daily
Q 01Male-to-female sex change is common in fish and molluscs but absent from which group?
Terrestrial vertebrates
Terrestrial vertebrates never switch from male to female, though the common frog Rana temporaria sometimes changes the other way, female to male.
Q 02What term describes an organism that produces male and female gametes at different stages in its life?
Sequential hermaphroditism
Sequential hermaphroditism is usually cued by social structure or by reaching a certain size or age; botanists call the plant version dichogamy.
Q 03Which term describes clownfish starting life as males and becoming females?
Protandry
Protandry runs the clownfish anemone: the breeding female is the largest fish, and if she dies the breeding male becomes the female and the largest non-breeder the male.
Q 04What is it called when an animal starts life as a female and later changes to a male?
Protogyny
Protogyny is by far the commoner direction in fish: about 75% of the roughly 500 known sequentially hermaphroditic fish species change from female to male.
Q 05In species like the bluehead wrasse, what typically triggers the largest female to change sex?
Removal of the dominant breeder
Removal of the dominant breeder is the cue: when terminal-phase males are taken away, more females turn into males, a change that takes around 8 days and can't be reversed.
Q 06From which sex does the Asian sheepshead wrasse (kobudai) typically transition to become a male?
From a female
After the transition the fish grows its famous bulbous forehead and turns aggressive, though it keeps some ovary-like gonad tissue from its female years.
Q 07What term describes fish that can switch sex back and forth between male and female?
Bidirectional hermaphroditism
Bidirectional hermaphroditism lets a fish switch sex either way, potentially repeatedly, which suggests there may be no inherent advantage to whichever sex it starts as.
Q 08Beyond social cues, what environmental factor influences sex determination in some fish and reptiles?
Temperature
Temperature settles sex in most turtles and some teleost fish, and near the 'pivotal' temperature, where its influence is equivocal, mixed sex ratios appear.
Q 09Which leading hypothesis says animals change sex because each sex reproduces best at a different growth stage?
The size-advantage hypothesis
The size-advantage hypothesis holds that each sex breeds best at a certain size: big bodies make more eggs, favouring male-first, but where a big male guards a harem, female-first pays.
Q 10Which key enzyme lets sex-switching fish convert androgens into oestrogens to transform their gonads?
Aromatase
Aromatase is the enzyme that turns androgens into oestrogens, and in some fish it turns up in the ovaries whether sex was set by genes or by temperature.