Name:_________________
Date: _________________
Summary sheet
(Sheet #6)
Grade 12
Ch. 28, 29
Lesson 28.1
How Animals Respond Information in the environment that causes an organism to react is called a
stimulus. A specific reaction to a stimulus is called a response. Stimulus like heat, temperature, odor, taste
etc…The nervous systems of animals help them respond to stimuli. Nervous systems are composed of
specialized nerve cells, or neurons.
Neurons that respond to stimuli are sensory neurons.
Neurons that typically pass information to still other neurons are called interneurons. Vertebrates have
more interneurons than invertebrates.
Motor neurons carry “directions” from interneurons to muscles.
▪
The neural circuit in the left is simpler than the one in the right.
In complex animals the sensory neurons detect a stimulus then
send information to the interneurons. Interneurons process
information and send it to the
motor neurons that give directions to the muscles.
Trends in Nervous System Evolution Animal nervous systems exhibit different degrees of
cephalization and specialization.
Cnidarians, such as jellyfishes, have simple nervous systems called nerve nets.
Other invertebrates have a number of interneurons that are grouped together into small structures called
ganglia.
Bilaterally symmetric animals often exhibit cephalization. Cephalization is the concentration of sensory
neurons and interneurons in a “head.”
In some species, cerebral ganglia are further organized into a structure called a brain. Vertebrate brains
include the following structures:
• The cerebrum is the “thinking” region of the brain. Learning, memory and conscious thought
• The cerebellum coordinates movement and controls balance.
• The medulla oblongata controls the functioning of many internal organs.
• Vertebrate brains are connected to the rest of the body by a thick collection of nerves called a spinal
cord, which runs through a tube in the vertebral column.
Biology/ Term 3/ grade 12
page 1
The cerebrum and cerebellum increase in size from fishes to mammals.
Sensory Systems Sensory systems range from individual sensory neurons to sense organs that contain
both sensory neurons and other cells that help gather information.
Many invertebrates have sense organs that detect light, sound, vibrations, movement, body orientation,
and chemicals in air or water.
Most vertebrates have highly evolved sense organs. Many vertebrates have very sensitive organs of taste,
smell, and hearing.
Animal
Flat worm (planarian)
Scallop
Arthropods( mosquitoes)
Octopi and squids
Sensory organ
Eyespot detect light
Simple eye detect movement
Compound eyes made up of many lenses that
detect minute changes in movement and color
produce less detailed images than human eyes
Complex eyes detect motion and color and form
images
How Animals Respond
1. What is a response?
A specific reaction to a stimulus is called a response.
2. What body systems interact to produce a behavior in response to a stimulus?
The sense organs, Nervous system, muscular system
Write the letter of the correct answer on the line at the left.
3. Which of the following is the best example of a stimulus?
A. sneezing
C. swallowing food
B. a bell ringing
D. holding your breath
4. Which of the following is the best example of a response?
A. hunger pains
C. a breeze blowing
B. a hot sidewalk
D. answering a phone
Biology/ Term 3/ grade 12
page 2
5. Complete the table about types of neurons.
Types of Neurons
Type of Neuron
interneuron
Description
neurons that pass information from one neuron to another
Sensory neurons
Neurons that respond to stimuli
Motor neurons
carry “directions” from interneurons to muscles.
Trends in Nervous System Evolution
6. THINK VISUALLY Label the nervous system structures in the following invertebrates. Circle the
organism that does NOT show cephalization.
For Questions 7–10, write True if the statement is true. If the statement is false, change the underlined word
or words to make the statement true.
True 7. Most mammals have color vision.
True
8. Flatworms use eyespots to detect light.
False
9. The complex eyes of many arthropods are made up of many eyespots.
False
10. Out of all the animal groups, invertebrates have the most highly evolved sensory organs.
Biology/ Term 3/ grade 12
page 3
Lesson 28.2
Types of Skeletons There are three main types of animal skeletons:
Some invertebrates, such as cnidarians and annelids, have hydrostatic skeletons. A hydrostatic skeleton
consists of fluids held in a gastrovascular cavity that can alter the animal’s body shape drastically by working
with contractile cells in its body wall.
An exoskeleton, or external skeleton, of an arthropod is a hard body covering made of a carbohydrate
called chitin. Most mollusks have exoskeletons, or shells, made of calcium carbonate. To increase in size,
arthropods break out of their exoskeleton and grow a new one in a process called molting. They can also
provide watertight coverings that enable some arthropods to live in Earth’s driest places.
An endoskeleton is a structural support system within the body. Vertebrates have an endoskeleton made of
cartilage (ex: sharks) or a combination of cartilage and bone. (also echinoderms, such as sea stars, have
endoskeleton)
Arthropods and vertebrates can bend because many parts of their skeletons are connected by joints. In
vertebrates, bones are connected at joints by strong connective tissues called ligaments.
Muscles and Movement Muscles are attached to and pull on different parts of an organism’s skeleton. This
causes movement.
Muscles are attached to bones around the joints by tough connective tissue called tendons.
The shapes and relative positions of bones and muscles, and the shapes of joints, are linked very closely to the
functions they perform.
Muscles often work in opposing groups. Flexors bend a joint. Extensors straighten a joint.
Muscles of arthropods are attached to the inside of the exoskeleton. Vertebrate muscles are attached around the
outside of bones.
➢ Types of Skeletons
1. What are the three main kinds of skeletal systems?
Endoskeleton, exoskeleton, hydrostatic
2. What is chitin?
a carbohydrate that makes up the hard exoskeleton of arthropods
Biology/ Term 3/ grade 12
page 4
3. Which invertebrates have endoskeletons?
Echinoderms (such as sea star)
4. Which animals have exoskeletons?
Some mollusks, arthropods
5. As you read the lesson, place the terms in the correct location in the chart.
ligament
joint
Term
tendon
Definition
How It Helps Movement
Joint
a place where parts of a skeleton are
held together
allows parts of a rigid skeleton to
bend
Tendon
strong connective tissue that holds
muscles to bones near joints
pulls on bones when muscles
contract
Ligament
strong connective tissue that holds
bones together at joints
connects bones to each other
Match the organism with its skeleton. A skeleton type may be used more than once.
Organism
Skeleton Type
A. hydrostatic skeleton
B
6. grasshopper
B. exoskeleton
A
7. jellyfish
C. endoskeleton
C
8. hawk
C
9. sea star
B
10. crab
A
11. earthworm
B
12. ant
C
13. dog
For Questions 14–16, write the letter of the correct answer on the line at the left.
14. What is the process by which an arthropod breaks out of an exoskeleton it has
outgrown?
A. molting
C. shedding
B. excreting
D. metamorphosing
Biology/ Term 3/ grade 12
page 5
15. The pieces of an exoskeleton move against each other along
A. chitin.
C. tendons.
B. joints.
D. cavities.
16. What type of structure connects one bone to another in a vertebrate skeleton?
A. a muscle
C. a ligament
B. a tendon
D. a tube foot
For Questions 17–22, complete each statement by writing the correct word or words.
17. Specialized tissues that produce physical force by contracting, or getting shorter, when
they are stimulated are called muscles.
18. When they are not being stimulated, muscles relax.
19. In many animals, muscles work in pairs on opposites sides of a joint.
20. Muscles are attached to bones around the joints by tough connective tissue called tendon.
21. When muscles contract, tendons pull on bones.
22. Arthropod muscles are attached to the inside of the exoskeleton.
Lesson 28.3
Asexual and Sexual Reproduction Most animals reproduce sexually. Some
animals are also able to reproduce asexually.
Asexual reproduction requires only one parent (benefit) allowing for rapid reproduction.
Female of some species, such as a whiptail lizard, can reproduce asexually by producing
eggs that develop without being fertilized. This process, called parthenogenesis, produces
offspring that carry DNA inherited only from their mothers. This means of reproduction
occurs in some crustaceans and insects but very rarely in vertebrates.
Asexual reproduction requires only one parent, so individuals in favorable environmental
conditions can reproduce rapidly.
Since offspring produced asexually carry only a single parent’s DNA, they have less
genetic diversity than do offspring produced sexually.
Sexual reproduction requires two parents, parents produce haploid gametes (sperm and
eggs) by meiosis. This type of reproduction maintains genetic diversity in a population by
creating individuals with new combinations of genes. In most animal species that
reproduce sexually, each individual is either male or female.
Among annelids, mollusks, and fishes, however, some species are hermaphrodites, which
means that some individuals can be both male and female or can convert from one sex to
the other.
Biology/ Term 3/ grade 12
page 6
A number of invertebrates have life cycles that
alternate between sexual and asexual
reproduction. Many cnidarians alternate
between two body forms: polyps that grow
singly or in colonies and medusas that swim
freely in the water. The life cycle of a common
jellyfish is shown in the figure. In these
jellyfish, polyps produce medusas asexually
by budding. The medusas then reproduce
sexually by producing eggs and sperm that are
released into the water. After fertilization, the
resulting zygote grows into a free-swimming
larva. The larva eventually attaches to a hard
surface and develops into a polyp that may continue the cycle.
Internal and External Fertilization In sexual reproduction, eggs and sperm meet
either inside or outside the body of the egg-producing individual.
During internal fertilization, eggs are fertilized inside the body of the egg-producing
individual. Invertebrates that reproduce by internal fertilization range in complexity from
sponges to arachnids.
The eggs of sponges and some other aquatic animals are fertilized by sperm released by
others of their species and taken in from the surrounding water. In many arthropod
species, males deposit sperm inside the female’s body during mating.
In external fertilization, eggs are fertilized outside the body.
Chordates with external fertilization include most nonvertebrate chordates and many
fishes and amphibians. In some fish species males and females spawn in a school, releasing
large numbers of eggs and sperm into the water. Other fishes and many amphibians spawn in
pairs. In these cases, the female usually releases eggs onto which the male deposits sperm.
Development and Growth Embryos develop either inside or outside the body of a
parent in various ways.
Oviparous species are those in which embryos develop in eggs outside the parents’
bodies. Example many fishes, amphibians, all birds
In ovoviviparous species, embryos develop within the mother’s body, but they depend
entirely on the yolk sac of their eggs. Example some sharks
Viviparous species’ embryos obtain nutrients from the mother’s body. Some mammals
nourish their embryos by means of a placenta—a specialized organ that enables
exchange of respiratory gases, nutrients, and wastes between the mother and her
developing young.
As invertebrates, nonvertebrate chordates, fishes, and amphibians develop, they undergo
metamorphosis, resulting in changes to their shape and form.
Biology/ Term 3/ grade 12
page 7
Some insects undergo gradual or incomplete metamorphosis. Immature forms, or
nymphs, resemble adults, but they lack functional sexual organs and some adult
structures like wings.
Other insects undergo complete metamorphosis. Larvae change into a pupa, the stage in
which an insect larva develops into an adult.
Reproductive Diversity in Chordates Chordates had to adapt to reproduction on
land. Most chordates need a wet or moist environment for their eggs.
The eggs of most aquatic organisms must develop in water. Reptiles, birds, and a few
mammals have evolved amniotic eggs in which an embryo can develop outside its
mother’s body, and out of water, without drying out.
Mammals have various reproductive adaptations, but all mammalian young are nourished
by milk produced by the mother’s mammary glands.
Sexual
Genetic diversity
Advantage
Disadvantage
Two parents are needed
Slow
Asexual
Rapid,
One parent is needed
No genetic diversity
Types of Mammalian Reproduction and Development
Group
Monotremes
Marsupials
Placental
mammals
How Are Young Born?
How Are Young Fed?
Young hatch from soft-shelled eggs laid Young get milk from
pores on the mother’s
outside the mother’s body.
abdomen
Embryo is born at a very early stage of
Young drink from a
development and attaches to a nipple
nipple inside the mother’s
inside a pouch.
pouch.
Embryos develop inside the mother.
Wastes and nutrients pass through the
placenta.
Biology/ Term 3/ grade 12
Young are generally
nursed by the mother.
page 8
Answer the following questions.
1. What does asexual reproduction allow animals to do?
To produce many of its kind.
2. What is an advantage of sexual reproduction?
It increases genetic diversity.
3. What is the difference between external and internal fertilization?
External fertilization takes place outside the body usually in water, while internal
fertilization takes place inside the body.
Write the letter of the correct answer on the line at the left.
4. In which mode of reproduction do the embryos develop inside the mother’s body
using the egg yolk for nourishment?
A. oviparous
C. viviparous
B. ovoviviparous
D. herbivorous
5. Organisms that develop placentas are
A. oviparous.
B. ovoviviparous.
C. viviparous.
D. herbivorous.
Lesson 29.1
Behavior and Evolution Behavior is the way an organism reacts to stimuli in its
environment.
Behaviors essential to survival and reproduction include finding and catching food,
selecting a habitat, avoiding predators, and finding a mate.
Some behaviors are influenced by genes and can be inherited.
Certain behaviors evolve under the influence of natural selection:
• If a behavior increases an individual’s fitness and is influenced by genes, it tends to
spread through a population.
• Over many generations, adaptive behaviors can prove important in the survival of
populations and species.
Innate Behavior An innate behavior, also called an instinct, is fully functional the first time
it is performed, although the animal has no previous experience with the stimulus. All innate
behaviors depend on patterns of nervous system activity that develop through complex
interactions between genes and the environment.
The suckling of a newborn mammal is a classic example of a simple innate behavior. Other
innate behaviors, such as the weaving of a spider web or the building of hanging nests by
weaver birds, can be quite complex.
Biology/ Term 3/ grade 12
page 9
Learned Behavior Acquiring changes in behavior during one’s lifetime is called learning. There
are four types:
Habituation is the process by which an animal decreases or stops its response to a repetitive
stimulus that neither rewards nor harms the animal.
Example: Birds on the side of a road take flight when a car approaches. After the
passage of many cars, which haven’t harmed them, the birds no longer take flight when one
approaches. The birds have become habituated to the stimulus of passing cars.
In classical conditioning, a certain stimulus comes to produce a particular response, usually
through an association with a positive or negative experience.
Classical conditioning was first
described by Russian physiologist
Ivan Pavlov, who was studying dogs’
responses to food. Pavlov first noted
that dogs salivate as an innate
response to food. Then Pavlov
discovered that if he always rang a
bell when he offered food, a dog
would salivate whenever it heard a
bell, even if no food was present.
Pavlov’s experiment produced
salivation (a response) in reaction to
the bell (a stimulus) associated with
food.
Operant conditioning (a form of trial-and-error learning) is the use of a reward or
punishment to teach an animal to behave in a certain way through repeated practice.
Example: A dog randomly brushes its tail against a bell hanging on a doorknob. The owner
responds by opening the door to let the dog outside. After the “ring the bell; open the door“
sequence has occurred several times, the dog has learned to ring the bell when it wants to go out.
Insight learning occurs when an animal applies to a new situation something that it learned
previously in another context. It is common among humans and some other primates.
In one experiment, a hungry chimpanzee used insight learning to figure out how to reach a bunch
of bananas hanging overhead: It stacked some boxes on top of one another and climbed to the top
of the stack.
Complex Behaviors Many complex behaviors combine innate behavior with learning.
Imprinting is a complex behavior. Imprinting is the process by which some animals, such as
birds, recognize and follow the first moving object they see during a critical period in their early
lives
Biology/ Term 3/ grade 12
page 10
For Questions 1–5, write True if the statement is true. If the statement is false, change the
underlined word or words to make the statement true.
False, behavior
1. An adaptation is the way an animal responds to a stimulus in its
environment.
True
2. An animal’s nervous system makes behaviors possible.
True
3. Certain behaviors are influenced by genes and can therefore be inherited.
False, increases
4. If a behavior decreases fitness, it may spread in a population.
True
5. Adaptive behaviors can play a role in the survival of a species.
For Questions 6–9, write the letter of the correct answer on the line at the left.
6. Birds that are born recognizing the songs of their own species are exhibiting
A. innate behavior.
C. operant conditioning.
B. habituation.
D. insight learning.
7. Young birds following their mother is an example of
A. imprinting.
C. operant conditioning.
B. classical conditioning.
D. habituation.
8. Imprinting is considered a complex behavior because
A. it is adaptive.
B. it is instinctual.
C. it combines classical conditional and instinct.
D. it combines innate behavior with learning.
9. Once imprinting has occurred, the behavior becomes
A. complex.
B. fixed.
C. conditioned.
D. innate.
Lesson 29.2
Animals in Their Environments
Behavioral Cycles Many animals demonstrate daily or seasonal cycles in their behavior.
Circadian rhythms are behavioral cycles that occur daily.
Migration is the seasonal movement from one environment to another. For example, many
birds find food and nesting sites in the north in summer, but they fly south to warmer
climates for the winter.
Social Behavior Interactions among animals of the same species are social behavior. There
are several types:
Animals (usually the males) perform courtship behaviors to attract a mate. An elaborate
series of courtship behaviors is a courtship ritual.
Many animals occupy a specific area, or territory, that they defend against competitors.
Animals may use threatening behaviors, or aggression, to defend their territories. Animals
also may use aggression when they compete for resources.
Biology/ Term 3/ grade 12
page 11
Some animals form a society, or a group that interacts closely and often cooperatively.
Mammals form many types of societies, which offer a range of advantages. Zebras and other
grazers, for example, are safer from predators when they are part of a group than when they
are alone. The theory that helping a relative survive increases the chance of transmitting
one’s own genes is kin selection.
The most complex animal societies are those formed by social insects such as ants, bees, and
wasps. All animals in the society cooperate closely to perform complex tasks, such as nest
construction.
For Questions 1–5, complete each statement by writing the correct word or words.
1. Many animals respond to periodic changes with daily or seasonal cycles of behavior.
2. Behavioral cycles that occur daily are called circadian rhythms.
3. Seasonal dormancy in mammals is called hibernation.
4. The seasonal movement from one environment to another is migration.
5. Migration allows animals to take advantage of favorable environmental conditions.
Biology/ Term 3/ grade 12
page 12