L12 - Introduction to Animals

What are possible consequences of indeterminate cleavage?

- Identical twins in humans - The development of a complete embryo from the remaining three cells when one cell is excised from a four-cell embryo - The development of a complete embryo from a single cell excised from a four-cell embryo

Animals classified as radially symmetric ______, while animals classified as bilaterally symmetric ______.

- can be divided into similar halves by any plane along the main axis - when cut in only one plane, the two halves are mirror images of each other

Place the steps of germ layer formation in sequential order. Start with the earliest step on top.

1. Ferilization produces a zygote. 2. Cleavage. 3. Formation of a blastula. 4. Gastrulation begins. 5. Formation of distinct endoderm, mesoderm, and ectoderm.

Animals with radial symmetry have ___ germ layers, and animals with bilateral symmetry have ___ germ layers.

2 germ layers 3 germ layers

Which is a blastula?

A hollow sphere of cells produced early in the development of an animal embryo

Animals belonging to the group Bilateria exhibit what anatomical characteristics?

An anterior and a posterior end A dorsal and a ventral side Cephalization

Animals may be categorized into three types according to the type of symmetry their body displays. What are these?

Bilateral symmetry Radial symmetry No symmetry

Animals that are bilaterally symmetrical are placed in the group _______.

Bilateria

Animals that have a dorsal and a ventral side, have an anterior and posterior end, and exhibit cephalization belong to the ______.

Bilateria

Based on the type of symmetry that they display, animals such as grasshoppers, mice, and ostriches are placed in the group ____.

Bilateria

Based on the type of symmetry that they display, animals such as grasshoppers, mice, and ostriches are placed in the group ______.

Bilateria

What is indeterminate cleavage?

Cells formed during cleavage retain the ability to develop into a complete embryo when removed.

The ability to detect and respond to food by animals that encounter their environment initially with their head is an advantage gained through _____.

Cephalization

What characteristics are found in all animals?

Characteristic cell junctions Multicellularity Extracellular matrix Heterotrophic

What features are associated with animals that are radially symmetric?

Circular- or tubular-shaped with a mouth at one end Can be divided equally by any longitudinal plane passing through the central axis

The only phylum that is diploblastic is ______.

Cnidaria

Which animal group exhibit radial symmetry?

Cnidarians

What happens during gastrulation?

Different cell layers are produced in a developing embryo.

True or false: In determinate cleavage, the fate of each cell is determined relatively late so that removal of a single cell from the embryo has little effect on development.

False Reason: In determinate cleavage, the fate of each cell is determined relatively early, so that removal of a single cell causes development to discontinue.

What are germ layers?

Layers of cells in an embryo that form the organs

What advantages does the animal cell structure have?

Movement facilitated by flexibility Structure facilitated by an extracellular matrix Communication facilitated by cell junctions

Coordinated movement to capture prey or escape predators depends on interactions between what two systems?

Nervous system Musculoskeletal system

Match the following animals to their body symmetry. Parazoa Cnidaria Bilateria

Parazoa - no symmetry Cnidaria - radial symmetry Bilateria - "dual" symmetry

What type of cleavage pattern results in layers of cells that are lined up directly above one another?

Radial

How many embryonic germ layers do radially symmetric and bilaterally symmetric organisms have?

Radially symmetric organisms have two germ layers, while bilaterally symmetric organisms have three.

What are all the features of reproduction and development in animals.

Some animals reproduce sexually. Some animals reproduce asexually. Some animals undergo metamorphosis. Fertilization can occur externally. Fertilization can occur internally.

What animals would be placed in the group Bilateria?

Spider Horse Lobster

Animals are able to obtain the nutrients essential to life in what ways?

Suspension feeding Bulk feeding Fluid feeding Internal digestion

What are characteristics are correlated with bilateral symmetry?

The ability to move through the environment Cephalization

What are the characteristic features of protostome development?

The blastopore becomes the mouth. Determinate cleavage

What does the blastopore develop into in deuterostomes?

The blastopore develops into the anus.

What does determinate development mean?

The cells differentiate into tissues early in development.

What does the ectoderm and endoderm do?

The ectoderm differentiates into the nervous system and epidermis. TWhich is a blastula?he endoderm lines the digestive tract.

What statement best describes reproduction in animals?

They can reproduce sexually or asexually, and fertilization can occur externally or internally.

How do animals obtain the organic molecules necessary to sustain life?

They feed on other organisms or their products.

What is true about animals which are in the Bilateria group?

They have a left and right side that are mirror images of each other.

What is the difference between triploblastic and diploblastic animals?

Triploblastic animals develop a mesoderm, diploblastic animals do not.

What are features traditionally used by biologists to classify animal diversity?

Type of body symmetry Features of embryonic development Number of germ layers

The mesoderm is ______.

a layer of cells only found in animals that are bilaterally symmetrical

An animal is an organism best described as being ______.

a multicellular heterotroph that lacks cell walls and is motile at some point during its life cycle

Cephalization is an advantage in animals because it ______.

allows animals to better detect and consume prey allows for detection and response to predators and other encountered dangers

Multicellular heterotrophs lacking cell walls are known as _______.

animals

What end of the animal body is towards the front or head?

anterior

Cephalization and the ability to move through the environment to detect food and escape predators are found in animals that have ______ symmetry.

bilateral

An animal that can be divided only by a vertical plane along the midline to create two identical halves exhibits _______ symmetry, while an animal that can be divided into two identical halves by any longitudinal plane passing through the central axis exhibits ______ symmetry.

bilateral radial

In the animal kingdom, the majority of species are ______.

bilaterally symmetric

During embryonic development, a hollow sphere of cells called the ________ forms following rapid mitotic division of the zygote.

blastula

Protostomes display spiral and _____ cleavage.

determinate

Animals that undergo embryonic development where the blastopore develops into the animals' anus are called ______.

deuterostomes

In ______, the blastopore becomes the anus, and the mouth is formed from a secondary opening.

deuterostomes

Indeterminate cleavage is a characteristic of animals called ______.

deuterostomes

The upper surface of an animal, an organ, or a body part is the _____ side.

dorsal side

The nervous system and the epidermis arise from the embryonic germ layer called the _______.

ectoderm

What are the three germ layers called?

ectoderm, mesoderm, endoderm

The layer of cells that lines the primitive digestive tract (the archenteron) during gastrulation is called the _______ , while the layer of cells differentiating into the nervous system and epidermis is called the ________.

endoderm ectoderm

In the developing embryo, invagination of the blastula, known as ______, is necessary to allow germ layers to form.

gastrulation

The formation of different cell layers in a growing embryo is called ______.

gastrulation

Embryonic cell layers are called ______ ______.

germ layers

The anterior end of an animal's body is the ______ region of the body.

head

Animals cannot synthesize their own organic molecules using energy from inorganic substances, and so have to rely on other organisms for food. Therefore, they are called _______.

heterotrophs

Deuterostome development in most species is characterized by ______ cleavage.

indeterminate

During embryonic development, a cleavage in which each cell produced early on can develop into a complete embryo of the animal is called _____ cleavage.

indeterminate

In humans, identical twins can result because of the occurrence of ______ cleavage during embryonic development.

indeterminate

Ventral typically refers to the lower side of an animal's body______.

lower side of an animal's body

Only the Bilateria possess a third layer of embryonic cells, called the _____.

mesoderm

Unlike in deuterostomes, the blastopore of protostomes becomes which structure?

mouth

In protostomes, the blastopore becomes the ______ , while in deuterostomes, the blastopore becomes the _____.

mouth anus

A unique feature that animals use for purposes of acquiring food and escaping from predators is ______.

movement

The structure of animal cells can best be described as facilitating ______.

movement

Whereas plants are sessile and stay in one place, most animals are capable of _______ in order to capture food and avoid predators.

movement

Animals are _____.

multicellular heterotrophs without cell walls

Muscles are not enough to capture prey or escape predators. The muscles require coordination by the ______.

nervous system

Ectoderm is essential in the formation of the ______.

nervous system epidermis

The back or rear of the body is called the ______ end.

posterior

Animals that undergo embryonic development where the embryonic blastopore develops to become the animal's mouth are _______.

protostomes

What group of animals has determinate cleavage?

protostomes

The embryonic cleavage pattern resulting in cells that are aligned directly over each other because the cleavage planes are parallel or perpendicular to the vertical axis of the egg is ______ cleavage.

radial cleavage

Cnidarians (jellyfish and coral) are ______ symmetric animals.

radially

Animals that can be divided equally by any longitudinal plane passing through the central axis are said to be ______ symmetric, while animals that can be divided along a vertical plane at the midline to create two halves are _______ symmetric.

radially bilaterally

Animals that are circular or tubular in shape are typically ______.

radially symmetric

What type of cell cleavage results in layers of cells where the upper cells are aligned between the cells of the lower layer?

spiral

The type of cleavage that occurs when developing cells in a blastula do not align directly over each other, but instead lie at an angle to each other, is called ______ cleavage.

spiral cleavage

A major difference in embryo development between sponges and other animals is ______.

sponge embryos do not develop germ layers

Some of the earliest-diverging animals, such as ______ , had no plane of symmetry.

sponges

Which groups of animals are asymmetric?

sponges

Unlike in other animals, the embryos of ______ do not develop Germ layers.

sponges / Parazoa / Porifera

Animals use a variety of methods to obtain nutrients, including _______ feeding, ________ feeding, and _______ feeding.

suspension feeding bulk feeding fluid feeding

Animals can be divided into categories according to the type of ______ their body displays.

symmetry

When an animal has balanced proportions of the body on either side of a median plane, then the animal is said to have body ______.

symmetry

What is the posterior end of the body?

the back or rear

Most animals have three embryonic germ layers and are therefore called _____.

triploblastic

Animals of the Bilateria with all three distinct germ layers are referred to as ______ , whereas ______ refers to animals of the Radiata that have only two germ layers.

triploblastic diploblastic

Morphological and developmental features typically used to classify animals into taxonomic groups include ______.

type of body symmetry, number of germ layers, and features of embryonic development

Dorsal refers to the ______.

upper side of an animal's body

The underside or lower surface of the body is called the ______ side.

ventral