Chapter 43: Animal Reproduction

BSC2011C Fall '25

Asexual reproduction produces genetically ___ offspring

Identical

What kind of reproduction allows for quick production of offspring?

Asexual

In stable and predictable environments, what kind of reproduction is favorable?

Asexual

When colonizing new habitats, what type of reproduction is favored?

Asexual

Sexual reproduction produces genetically ___ offspring

Different

Sexual reproduction ____ genetic diversity

Increases

In unstable and unpredictable environments, what kind of reproduction is favorable?

Sexual

What’s a disadvantage to sexual reproduction?

Requires both sexes to reproduce

What happens during binary fission?

Organism splits into two separate, equally sized organisms

In who can binary fission occur?

Invertebrate multicellular organisms

In who can binary fission occur?

Corals, anemones

What is budding?

Adult organism creates an outgrowth who eventually separates/grows into another separate adult organism

In who does budding occur?

Some invertebrates

What is fragmentation?

Part of the adult body breaks off and each parts undergoes regneration

In who does fragmentation occur?

Sea stars, flatworms, Poriferans (sponges)

What is parthenogenesis?

In females, two eggs fuse with each other

In who can parthenogenesis occur?

Water fleas, bees, daphnia, reptiles, amphibians, fish

In mammals, what chromosome combination indicates females?

XX

In mammals, what chromosome combination indicates males?

XY

In birds, what chromosome combination indicates female?

ZW

In birds, what chromosome combination indicates male?

ZZ

In mammals, the genes on the __ chromosomes determine sex, while in birds, the genes on the _ determine sex

Y; W

In some animals __ is determined by __ not chromosomes

Sex; temperature

In turtles, what temperature makes them male?

Cooler temperatures

In turtles, what temperature makes them female?

Warmer temperature

In alligators/crocodiles, what temperature makes them male?

Warmer temperature

In alligators/crocodiles, what temperature makes them female?

Cooler temperatures

What does protogyny mean?

Organism was female first

What does protandry mean?

Organism was male first

Sex change throughout one’s life is common among what kind of animal?

Fish and oysters

In haplodiploid sex determination, haploids are what sex?

Male

In haplodiploid sex determination, diploids what sex?

Female

In what organisms can haplodiploid sex determination be seen?

Hymenoptera

What does monoecious mena?

An organism has both female/male reproductive parts

What organisms are monoecious?

Worms, slugs, snails

Where does external fertilization occur?

Aquatic environments

How does external fertilization occur?

Females release eggs and males release eggs into water at the same time

In external fertilization, broadcast spawning is triggered by what?

Time of year/day

In external fertilization, courtship spawning is triggered by what?

Courtship behavior

In broadcast spawning, how are the gametes released?

Both female/males release their gametes at the same time

In courtship spawning, how are gametes released?

Both female/males release their gametes at the same time in the same area

External fertilization produces a ___ number of offspring BUT a ___ rate of survival

Large; low

What is the process of internal fertilization?

Male sperm is deposited inside female to fertilize eggs

Internal fertilization produces a ___ number of offspring BUT a ___ rate of survival

Low; High

What are the three ways of offspring production (internal fertilization)?

Viviparous, Oviparous, Ovoviviparous

What happens in viviparous reproduction?

Egg sac with embryo attaches to mother’s oviduct and embryo obtains nutrition from mother and then born alive

What happens in oviparous reproduction?

Fertilized eggs are laid outside mother's body

What happens in ovoviviparous reproduction?

Fertilized eggs develop in mother's body, hatch in utero and then born alive

What kind of reproduction is live birth?

Viviparous

Most mammals use what kind of reproduction?

Viviparous

In oviparous and ovoviviparous reproduction, where does the embryo obtain nutrition?

Egg yolk

Most fish, reptiles and birds use what kind of reproduction?

Oviparous

In ovoviviparous reproduction, when are the young fully developed?

When they hatch inside the mother’s body

In some sharks, how do the young obtain nutrition?

By eating their siblings

Some sharks, snakes, and lizards use what kind of reproduction?

Ovoviviparous

What is spermatogenesis?

Production of sperm by male testes

Where can spermatogonia be found?

Testes

One spermatogonium goes through ___ to produce ___ ___ cells

Mitosis; two diploid

What happens to the two diploid cells made from spermatogonium?

One becomes another spermatogonium and the other becomes a primary spermatocyte

What does a primary spermatocyte produce?

Sperm by meiosis

Primary spermatocytes go through what process to make two secondary spermatocytes?

Meiosis I

Secondary spermatocyte go through what process to produce four cells?

Meiosis II

What do the four cells secondary spermatocytes produce?

Spermatids

What do spermatids differentiate into?

Sperm cells

When do spermatids differentiate?

When they reach the lumen of the seminiferous tubules

Spermatogonia are ___ but ___ at birth

Present; inactive

How are spermatogonia activated?

In puberty, gonadotropic hormones from the anterior pituitary activate the cells

What is oogenesis?

Production of eggs in ovaries

Where can oogonia be found?

Ovaries

Oogonium go through ___ mitosis to produce ___ ____ cells

Mitosis; two diploid

What are the two diploid cells produced by oogonium called?

Primary oocytes

Primary oocytes begin ___ but stop in ____ of meiosis I

Meiosis; Prophase I

When females are born, her eggs are…

Arrested in prophase I

How are the arrested female eggs released?

In puberty, gonadotropic hormones from the anterior pituitary/follicle stimulating hormone triggers the primary oocyte to finish meiosis I

Once the eggs are released after being arrested what is produced?

Two haploid cells that are unequal in size

What happens to the two female haploid cells?

The large one becomes a secondary oocyte and is arrested in Metaphase II of meiosis while the smaller one becomes a polar body

What happens to the secondary oocyte?

It’s released during ovulation

What happens if the secondary oocyte is fertilized?

It completes meiosis II and produces one zygote and a second polar body that degenerates