Biology Chapter 46: Animal Reproduction

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Questions and Answers

What is the main difference between sexual and asexual reproduction?

The fusion of gametes to form an offspring. (correct)

The environment in which reproduction takes place.

The number of offspring produced.

The type of gametes produced.

Which of the following animals is most likely to reproduce asexually?

Human

Hydra (correct)

Fish

Bird

What is the primary function of the epididymis in the male reproductive system?

To regulate the production of testosterone.

To propel sperm through the vas deferens.

To store sperm. (correct)

To produce sperm.

What is the main advantage of internal fertilization?

It enables sperm to reach an egg even in a dry environment. Signup and view all the answers

What is the primary function of the oviduct in the female reproductive system?

To convey eggs to the uterus. Signup and view all the answers

What is the process by which gametes are produced from germ cells?

Gametogenesis Signup and view all the answers

What is the primary function of FSH and LH in the reproductive system?

To regulate the production of sex hormones. Signup and view all the answers

What is the term for the end of ovarian and menstrual cycles in females?

Menopause Signup and view all the answers

What is the hormone that stimulates the uterus to contract during childbirth?

Oxytocin Signup and view all the answers

Where does fertilization typically occur in the female reproductive system?

Oviduct Signup and view all the answers

What is the primary function of dendrites in a neuron?

To receive signals from other neurons Signup and view all the answers

What type of neuron transmits information about external stimuli such as light, touch, or smell?

Sensory neuron Signup and view all the answers

What is the term for the junction between an axon and another cell?

Synapse Signup and view all the answers

What is the primary function of glial cells?

To support neurons Signup and view all the answers

What is the term for the membrane potential of a neuron that is not sending signals?

Resting potential Signup and view all the answers

What triggers a depolarization in a neuron?

Opening of Na+ channels Signup and view all the answers

What is the result of a depolarization that shifts the membrane potential sufficiently?

A massive change in membrane voltage called an action potential Signup and view all the answers

What type of process is an action potential?

All or none process Signup and view all the answers

Which of the following is an example of a neurotransmitter?

Chemical messenger Signup and view all the answers

What is the function of the hypothalamus in the brain?

Regulation of body temperature and biological clock Signup and view all the answers

What is the term for the clustering of sensory organs at the front end of the body in bilaterally symmetrical animals?

Cephalization Signup and view all the answers

What is the function of the cerebellum in the hindbrain?

Coordination of movement and balance Signup and view all the answers

What is the term for the ability of the nervous system to be remodeled after birth?

Neuronal plasticity Signup and view all the answers

What is the largest structure in the brain, essential for language, cognition, memory and consciousness?

Cerebrum Signup and view all the answers

What is the term for the system consisting of neurons carrying information in and out of the CNS?

Peripheral nervous system Signup and view all the answers

What is the primary focus of ecosystem ecology?

Studying energy flow and chemical cycling between organisms and the environment Signup and view all the answers

What is the main characteristic of tropical rain forests?

Constant rainfall and high year-round temperatures Signup and view all the answers

What is the primary adaptation of plants in desert biomes?

Reduced leaf surface area to conserve water Signup and view all the answers

Which of the following biomes is characterized by warm temperatures and dominant grasses and forbs?

Savanna Signup and view all the answers

What is the main human impact on chaparral biomes?

Urbanization and agriculture Signup and view all the answers

What is the term for long-term prevailing weather conditions in an area?

Climate Signup and view all the answers

Which of the following biomes is characterized by highly seasonal precipitation?

Temperate grassland Signup and view all the answers

What is the primary focus of population ecology?

Examining the factors that affect population size and growth Signup and view all the answers

What is the primary characteristic of terrestrial biomes?

Defined by vegetation type or physical environment Signup and view all the answers

Which of the following is an example of a terrestrial biome?

Desert Signup and view all the answers

What is the primary characteristic of tundra biomes?

Permafrost restricts the growth of plant roots Signup and view all the answers

What is the term for the mixing of waters in lakes that occurs in the spring and autumn?

Turnover Signup and view all the answers

Which of the following biomes is characterized by estuaries, intertidal zones, and ocean pelagic zones?

Marine biome Signup and view all the answers

What is the term for the process by which two evolutionarily unrelated species may live within the same type of biome but on different continents?

Convergent evolution Signup and view all the answers

Which human impact is associated with the tundra biome?

Oil and mineral extraction Signup and view all the answers

What is the characteristic of freshwater biomes in terms of salt concentration?

Salt concentration is less than 0.1% Signup and view all the answers

What is the primary human impact on the ocean pelagic zone?

Overfishing, pollution, ocean acidification, and global warming Signup and view all the answers

What type of biome is characterized by a nutrient-rich and productive transition zone between a river and the sea?

Estuary Signup and view all the answers

Which biome is the largest terrestrial biome?

Coniferous forest Signup and view all the answers

What is the primary human impact on wetlands?

Draining and filling Signup and view all the answers

What is the term for the pattern of spacing among individuals within the boundaries of the population?

Population dispersion Signup and view all the answers

Which type of survivorship curve is typically found in large mammals?

Type I Signup and view all the answers

What is the method of estimating population density by capturing, marking, and releasing individuals, and then recapturing them to estimate population size?

Mark-release-recapture method Signup and view all the answers

What is the term for the maximum population size that a particular environment can sustain?

Carrying capacity Signup and view all the answers

What is the term for a population density of individuals per unit area?

Population density Signup and view all the answers

What type of factors limit the population size when a death rate increases or a birth rate decreases with increasing density?

Density-dependent factors Signup and view all the answers

Which type of population dispersion is characterized by individuals being evenly spaced?

Uniform Signup and view all the answers

What is the term for the study of populations, focusing on characteristics such as population size, density, and dispersion?

Population ecology Signup and view all the answers

What is the term for the aggregate land and water area needed to sustain a person, city, or nation?

Ecological footprint Signup and view all the answers

What happens to the population growth rate when N is large and resources are limiting?

It decreases Signup and view all the answers

What is the term for the study of the changes in population size over time?

Population dynamics Signup and view all the answers

What type of factors limit the population size when a birth rate or death rate does not change with population density?

Density-independent factors Signup and view all the answers

What happens to the population when N equals K?

It stops growing Signup and view all the answers

What type of interaction occurs when individuals of different species use a resource that limits survival and reproduction of both individuals?

Competition Signup and view all the answers

Which type of interaction involves an individual of one species killing and eating an individual of another species?

Predation Signup and view all the answers

What is the term for the differentiation of niches that enables similar species to coexist in a community?

Resource partitioning Signup and view all the answers

Which type of defense mechanism involves bright warning coloration?

Aposematic coloration Signup and view all the answers

What is the term for the feeding relationships between organisms in a community?

Trophic structure Signup and view all the answers

What is the term for the local elimination of the inferior competitor?

Competitive exclusion Signup and view all the answers

What is the term for the ability of two or more unpalatable species to resemble each other?

Mullerian mimicry Signup and view all the answers

What is the term for the number of different species in a community?

Species richness Signup and view all the answers

What is the term for the transfer of energy from autotrophs to herbivores to carnivores?

Energy pyramid Signup and view all the answers

What is the term for the last link in a food chain?

Decomposer Signup and view all the answers

What is the primary reason for the limitation of food chain length?

Inefficient energy transfer Signup and view all the answers

Which type of species has strong effects due to their large size or high abundance?

Foundation species Signup and view all the answers

What is the term for species that exert strong control on a community?

Keystone species Signup and view all the answers

What is the term for species that create or dramatically alter their physical environment?

Ecosystem engineers Signup and view all the answers

What is the term for the pattern of colonization and species replacement that occurs in a community following a severe disturbance?

Ecological succession Signup and view all the answers

What is the primary difference between primary and secondary succession?

Presence or absence of soil Signup and view all the answers

Which type of species is more likely to have community-wide effects?

Foundation species Signup and view all the answers

What is the main characteristic of species that have strong ecological roles?

Pivotal ecological roles Signup and view all the answers

What is the primary source of energy for most ecosystems?

Solar energy Signup and view all the answers

Which trophic level consists of carnivores that eat herbivores?

Secondary consumer Signup and view all the answers

What is the percentage of production transferred from one trophic level to the next?

10% Signup and view all the answers

What is the primary function of decomposers in an ecosystem?

To break down organic matter Signup and view all the answers

Which carbon reservoir is responsible for storing the largest amount of carbon?

Soils and sediments Signup and view all the answers

What is the primary way that CO2 is removed from the atmosphere?

Through photosynthesis Signup and view all the answers

What is the term for the process by which CO2 is released into the atmosphere through the burning of fossil fuels and wood?

Carbon emission Signup and view all the answers

What is the term for the study of the dynamics of ecosystems?

Ecosystem ecology Signup and view all the answers

What is a major threat to biodiversity?

Habitat loss Signup and view all the answers

What is the term for the process where primary production increases as an ecosystem changes from nutrient-poor to nutrient-rich?

Eutrophication Signup and view all the answers

What is the term for the concentration of toxins in organisms at higher trophic levels?

Biological magnification Signup and view all the answers

What is the primary driver of climate change?

Human activities releasing gaseous waste into the atmosphere Signup and view all the answers

What is the term for a small area with numerous endemic and many endangered and threatened species?

Biodiversity hotspot Signup and view all the answers

What is the most common type of marine waste?

Microplastics Signup and view all the answers

What is the result of inbreeding and genetic drift in a small population?

Extinction vortex Signup and view all the answers

What is the primary consequence of overharvesting?

Decreased population size Signup and view all the answers

What is the term for the alteration of climate, atmospheric chemistry, and broad ecological systems that reduce Earth’s capacity to support life?

Global change Signup and view all the answers

What is the primary driver of species displacement?

Introduced species Signup and view all the answers

Study Notes

Animal Reproduction

Types of Reproduction

Sexual reproduction: creation of offspring by fusion of haploid gametes (egg and sperm)
Asexual reproduction: creation of offspring without fusion of egg and sperm
Advantages of sexual reproduction: increased genetic diversity, adaptation to environment
Advantages of asexual reproduction: rapid reproduction, conservation of energy
Disadvantages of asexual reproduction: limited genetic diversity, susceptibility to disease

Examples of Animals

Asexual reproduction: budding of sponges and hydra, more primitive forms of animals
Sexual reproduction: most vertebrate animals, including humans

Fertilization

Internal fertilization: occurs within an organism, enables sperm to reach an egg in a dry environment
External fertilization: occurs outside an organism, requires a moist habitat to prevent gametes from drying out
Fertilization: union of egg and sperm, resulting in the formation of a zygote

Reproductive Organs

Gonad: organs that produce gametes (testes in males, ovaries in females)
Male reproductive organs: seminiferous tubules, epididymis, vas deferens, urethra
Female reproductive organs: ovaries, oviduct (fallopian tube), uterus (womb)

Gametogenesis

Gametogenesis: production of gametes from germ cells
Spermatogenesis: formation of sperm, resulting in 4 sperm
Oogenesis: development of a mature egg, resulting in 1 egg, prolonged process

Hormones in Reproduction

Hypothalamus: secrets GnRH, directing release of FSH and LH from the anterior pituitary
FSH and LH: stimulate sex hormone production by gonads (testosterone, estrogens: estradiol and progesterone)
Oxytocin: stimulates the uterus to contract (positive feedback)

Menstrual and Ovarian Cycles

Regulated by sex hormones
Menopause: end of ovarian and menstrual cycles in females

Conception

Fertilization of an egg by a sperm, occurring in the oviduct (fallopian tube)

Neurons

Neurons are nerve cells that transfer information within the body.
A neuron consists of a cell body, dendrites, and an axon.

Structure of a Neuron

Cell body: contains most of the neuron's organelles.
Dendrites: highly branched extensions that receive signals from other neurons.
Axon: longer extension that transmits signals to other cells at synapses.

Synapses and Neurotransmitters

Synapse: a junction between an axon and another cell.
Neurotransmitters: chemical messengers that pass information from the transmitting neuron to the receiving cell at synapses.

Types of Neurons

Sensory neurons: transmit information about external stimuli such as light, touch, or smell.
Interneurons: integrate (analyze and interpret) the information.
Motor neurons: transmit signals to muscle cells, causing them to contract.

Glial Cells

Glial cells (Glia): supporting cells that aid neurons in their functions.

Mechanisms of Signal Transmission

Resting potential: the membrane potential of a neuron that is not sending signals, characterized by:
- Many open K+ channels and fewer open Na+ channels.
- K+ diffuses out of the cell, resulting in a buildup of negative charge within the neuron.
Action potential: changes in membrane potential, signals conducted by axons, involves:
- Opening other types of ion channels, triggering a depolarization.
- A reduction in the magnitude of the membrane potential.
- If a depolarization shifts the membrane potential sufficiently, it results in an action potential (all or none process, requiring a threshold).

Nervous Systems

A nerve is a bundle of axons from multiple neurons.
The nervous system has two main divisions: the central nervous system (CNS) and the peripheral nervous system (PNS).
CNS consists of the brain and spinal cord, while PNS consists of neurons that carry information to and from the CNS.

Glial Cells

Glial cells are supporting cells of neurons that provide nourishment, support, and regulation.

Brain Structure

The forebrain consists of the cerebrum, thalamus, hypothalamus, and amygdala.
The cerebrum is the largest structure in the brain and is essential for language, cognition, memory, and consciousness.
The hypothalamus is a control center that regulates body temperature and biological clock.
The amygdala is responsible for storing and recalling emotional memory.

Brain Regions

The midbrain is a region of the brain.
The hindbrain consists of the cerebellum, medulla, and pons.
The cerebellum coordinates movement and balance, and helps in learning and remembering motor skills.

Cephalization

Cephalization is the clustering of sensory organs at the front end of the body, characteristic of bilaterally symmetrical animals.

Neuronal Plasticity

Neuronal plasticity refers to the ability of the nervous system to be remodeled or reorganized after birth.

Ecology and the Biosphere

Ecology is the scientific study of the interactions between organisms and the living and nonliving components of their environment.
There are four main branches of ecology: population ecology, community ecology, ecosystem ecology, and biosphere ecology.

Climate

Climate refers to the long-term prevailing weather conditions in an area.
The four major components of climate are temperature, precipitation, sunlight, and wind.

Biomes

Biomes are major life zones characterized by vegetation type or physical environment.
There are two main categories of biomes: terrestrial biomes and aquatic biomes.

Terrestrial Biomes

Tropical rain forests: dominated by broadleaf evergreen trees, vertically layered, and intense competition for light.
Deserts: occur in bands near 30° north and south of the equator, with low and highly variable precipitation.
Savannas: warm year-round, with dominant plants being grasses and forbs.
Chaparral: occurs in mid-latitude coastal regions, with highly seasonal precipitation and dominated by shrubs.
Temperate grasslands: precipitation is highly seasonal, with dry winters and wet summers.
Coniferous forests: the largest terrestrial biome, with annual precipitation of 30-70cm and dominant vegetation being evergreen conifers.
Temperate forests: significant amount of precipitation, with dominant plants being deciduous trees.
Tundra: cold winters, with permafrost restricting the growth of plant roots.

Aquatic Biomes

Oceans: cover 75% of the Earth's surface, with a salt concentration of 3%.
Two types of aquatic biomes: marine biomes and freshwater biomes.
Marine biomes:
- Estuaries: nutrient-rich and productive transition zones between a river and the sea.
- Intertidal zones: periodically submerged and exposed by the tides.
- Ocean pelagic zones: expanses of open water.
- Coral reefs: formed from the calcium carbonate skeletons of corals, highly diverse species.
- Marine benthic zones: consist of the seafloor below the surface waters of the coastal, deep sea hydrothermal vents.
Freshwater biomes:
- Lakes: undergo a mixing of their waters called turnover in the spring and autumn.
- Wetlands: inundated by water at least some of the time, supporting plants adapted to water-saturated soil.
- Streams and rivers: current (headwater vs. downstream).

Convergent Evolution

Convergent evolution: two evolutionarily unrelated species may live within the same type of biome but on different continents.

Population Ecology

A population is a group of individuals of the same species living in an area.

Population Density

Population density is the number of individuals per unit area.
It can be examined by counting, sampling method, checking animal droppings, and mark-recapture method.

Population Dispersion

Population dispersion refers to the pattern of spacing among individuals within the boundaries of the population.
There are three types of population dispersion: clumped, uniform, and random.
Clumped: individuals aggregate in patches.
Uniform: individuals are evenly spaced.
Random: the position of each individual is independent of others.

Survivorship Curves

Survivorship curves are a plot of the proportion of numbers in a cohort still alive at each age.
There are three types of survivorship curves: Type I, Type II, and Type III.
Type I: Low death rates during early and middle life and a sharp increase in death rates later in life, found in large mammals.
Type II: Constant death rate over the life span, found in some rodents, invertebrates, lizards, and annual plants.
Type III: High death rates for the young; death rate steeply declines for survivors of early period die-off, found in organisms that produce very large numbers of offspring but provide little or no care.

Population Growth

Population growth can be exponential or logistic.
Change in population size = births – death.
Carrying capacity (K) is the maximum population size that a particular environment can sustain.
When N (population size) is small compared to K, the population grows rapidly.
When N is large and resources are limiting, the population grows slowly.
When N equals K, the population stops growing.

Factors Limiting Population Size

There are two types of factors that limit population size: density-dependent and density-independent.
Density-dependent factors: when a death rate increases or a birth rate decreases with increasing density (e.g. disease, competition).
Density-independent factors: A birth rate or death rate that does not change with population density (e.g. natural disaster).

Population Dynamics

Population dynamics refer to the fluctuations in population size over time.
Some populations fluctuate at unpredictable intervals, while others undergo regular boom-and-bust cycles (e.g. snowshoe hares and lynx).

Ecological Footprint

An ecological footprint summarizes the aggregate land and water area needed to sustain a person, city, or nation.

Interspecific Interactions

Interspecific interactions occur between individuals of different species
Competition: when individuals of different species use a limited resource, affecting survival and reproduction of both
Competitive exclusion: local elimination of the inferior competitor due to shared resource use
Resource partitioning: differentiation of niches enabling coexistence of similar species, possible in time and space

Types of Interspecific Interactions

Exploitation: one species benefits, the other is harmed (e.g., predation, herbivory, parasitism)
Predation: a predator kills and eats a prey species
Herbivory: an herbivore eats parts of a plant or alga
Parasitism: a parasite derives nourishment from a host, harming it
Mutualism: both species benefit
Commensalism: one species benefits, the other is neither harmed nor helped

Defense Mechanisms of Prey

Aposematic coloration: bright warning coloration
Cryptic coloration: camouflage
Batesian mimicry: a harmless species mimics a harmful model
Mullerian mimicry: multiple unpalatable species resemble each other

Community Ecology

Species diversity: composed of species richness and relative abundance
Trophic structure: feeding relationships between organisms in a community
Energy transfer: from autotrophs to herbivores to carnivores, with decomposers as the final link
Energetic hypothesis: food chain length is limited by inefficient energy transfer
Foundation species: have strong effects due to their size or abundance, providing habitat or food
Keystone species: exert strong control through pivotal ecological roles, despite not being abundant
Ecosystem engineers: create or alter their physical environment

Ecological Succession

Pattern of colonization and species replacement following a severe disturbance
Primary succession: occurs in areas with no previous vegetation
Secondary succession: occurs in areas with previous vegetation, but was disturbed or destroyed

Ecosystems

An ecosystem is composed of all living organisms in an area and the abiotic factors with which they interact.
Ecosystem dynamics involve two main processes: energy flow and chemical cycling.

Energy Flow

Energy enters most ecosystems as sunlight.
Autotrophs convert sunlight into chemical energy through photosynthesis.
Chemical energy is passed to heterotrophs as food.
Energy is eventually dissipated as heat.

Trophic Levels

Primary producers: autotrophs that build organic molecules using sunlight or inorganic compounds as energy sources.
Examples of primary producers include photosynthetic plants, algae, and prokaryotes.
Primary consumers: herbivores that eat primary producers.
Secondary consumers: carnivores that eat herbivores.
Tertiary consumers: carnivores that eat other carnivores.
Decomposers: heterotrophs that obtain energy from detritus, including prokaryotes and fungi.

Trophic Efficiency

Trophic efficiency is the percentage of production transferred from one trophic level to the next.
Average trophic efficiency is about 10%.

The Carbon Cycle

Photosynthetic organisms convert CO2 into organic molecules.
Carbon reservoirs include:
- Fossil fuels
- Soils and sediments
- Dissolved compounds in oceans
- Living biomass
- The atmosphere
- Sedimentary rocks
CO2 is taken up through photosynthesis and released through cellular respiration.
Volcanoes and the burning of fossil fuels and wood contribute significant amounts of CO2 to the atmosphere.

Biodiversity and Threats

Biodiversity encompasses genetic diversity, species diversity, and ecosystem diversity
Habitat loss has caused the greatest number of extinctions on record
Introduced species compete with native species and displace them, leading to extinctions
Overharvesting occurs when organisms are harvested at rates exceeding the ability of their populations to rebound
Global change refers to alterations in climate, atmospheric chemistry, and broad ecological systems that reduce Earth's capacity to support life

Biodiversity Hotspots and Ecosystem Disruptions

Biodiversity hotspots are relatively small areas with numerous endemic and endangered species
Eutrophication occurs when an ecosystem changes from nutrient-poor to nutrient-rich, leading to algal blooms and "dead zones"
Biological magnification occurs when toxins are passed up the food chain and concentrated in organisms at higher trophic levels

Plastics and Climate Change

Plastics are the most common type of marine waste, with microplastics being a significant concern
Human activities are driving climate change through the release of gaseous waste into the atmosphere, leading to a steady increase in atmospheric CO2 over the past 170 years
Burning fossil fuels and deforestation are the major factors driving climate change

Mass Extinctions

Previous mass extinctions have been caused by rise of sea levels, continental drift, intense volcanic activity, climate change, and meteor impact
The current potential 6th mass extinction, known as the Holocene, is driven by human activities
Mass extinction can pave the way for adaptive radiation by eliminating many species and allowing new ones to arise and adapt to different ecological niches
Pathogens can evolve more efficient forms of reproduction in new environments due to the lack of resistance in hosts through natural selection.

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Explore the differences between sexual and asexual reproduction in animals, including their advantages and disadvantages, and examples of each in various species.