4B1 Characteristics of Animals

Question 1

What is an animal body plan?

Answer 1

The organization and combination of an animal’s body parts and features, including body symmetry, disposition of limbs, and structure of organs and tissues.

Most types of animal body plans arose after the Cambrian Explosion, around 542 million years ago.

Question 2

What are some important features in animal body plans?

Answer 2

• Types of body symmetry.
• Structures such as body cavities and tissues.
• Patterns of body segmentation.
• Order of embryological development.

Question 3

What are the three common types of body symmetry in animal body plans?

Answer 3

• Asymmetry
• Radial Symmetry
• Bilateral Symmetry

Question 4

What is the type of symmetry where an animal’s halves mirror each other?

Answer 4

Bilateral symmetry

Question 5

Define:

Radial symmetry

Answer 5

A type of symmetry where body parts are arranged around a central axis, so any longitudinal plane through the central axis results in similar halves.

Question 6

What type of symmetry do humans and all other mammals have?

Answer 6

Bilateral symmetry

Question 7

What is the function of a coelom in animal body plans?

Answer 7

It is a fluid-filled body cavity completely lined with mesoderm, which allows internal organs to grow and move independently of the outer body wall.

Question 8

What distinguishes animals with true tissues?

Answer 8

Animals with true tissues have groups of specialized cells organized into functional units that perform specific tasks.

These animals are classified as eumetazoans.

Question 9

What is the term for animals in which the mouth develops first during embryonic development?

Answer 9

Protostomes

Question 10

What is the term for animals in which the anus develops first during embryonic development?

Answer 10

Deuterostomes

Question 11

What anatomical term refers to the head of an animal?

Answer 11

Anterior

Question 12

What anatomical term refers to the body region opposite an animal’s head?

Answer 12

Posterior

Question 13

What is the term for the backside of an animal?

Answer 13

Dorsal

Question 14

What is the term for the bottom side of an animal?

Answer 14

Ventral

Question 15

What is asexual reproduction?

Answer 15

A single individual contributes 100% of the genetic code to its offspring, leading to clones of the parent organism.

Example of asexual reproduction: budding.

Question 16

What are the characteristics of asexual reproduction?

Answer 16

Usually happens in simpler organisms, where any cell is capable of reproduction through mitosis, resulting in two identical cells.

Question 17

What is sexual reproduction?

Answer 17

Two individuals contribute genetic information to the offspring, creating a hybrid of the two parent organisms.

Question 18

What type of organisms more often use sexual reproduction?

Answer 18

Organisms with complex structures, including developed organ systems and specialized tissues, typically reproduce sexually.

Question 19

What is the process of making sex cells called?

Answer 19

Gametogenesis

Question 20

What is the difference between haploid and diploid cells?

Answer 20

• Haploid cells have half the genetic information as the parent cell.
• Diploid cells have all the genetic information.

Question 21

What is the function of gametes in sexual reproduction?

Answer 21

They are sex cells that come together during fertilization to form a zygote, which will develop into an individual.

In humans, gametes are known as sperm and egg.

Question 22

What triggers the release of the follicle from the ovary in females?

Answer 22

The luteinizing hormone (LH) in the pre-ovulation stage.

Question 23

What is the outcome of fertilization in sexual reproduction?

Answer 23

The formation of a zygote, which is the starting point for the development of an individual.

Question 24

What is a zygote?

Answer 24

A diploid cell formed by the fusion of two gametes. It contains the full genetic material and undergoes mitotic divisions to develop into an embryo.

Question 25

What is the process of **sperm production** called?

Answer 25

Spermatogenesis

Question 26

What are the **three main stages** of spermatogenesis?

Answer 26

1. Spermatocytogenesis 2. Spermatidogenesis 3. Spermiogenesis

Question 27

What is **spermatocytogenesis**?

Answer 27

The process by which diploid stem cells divide into haploid spermatocytes.

Question 28

What occurs in **spermatidogenesis**?

Answer 28

Secondary spermatocytes undergo meiosis II to form haploid spermatids.

Question 29

What is **spermiogenesis**?

Answer 29

The physiological change that spermatids undergo to become fully functional sperm cells.

Question 30

What is **mitosis**?

Answer 30

The process by which a single parent cell divides to **produce two genetically identical daughter cells**. ## Footnote In single-celled organisms, mitosis can result in asexual reproduction.

Question 31

# Define: meiosis

Answer 31

The type of cell division that **reduces the chromosome number by half**, producing haploid gametes (sperm and eggs) for sexual reproduction. ## Footnote Female sex cells are **oocytes** and male sex cells are **spermatocytes**.

Question 32

What is the process of **creating ova** called?

Answer 32

Oogenesis

Question 33

What are **hermaphrodites**?

Answer 33

Organisms that have **both male and female** sexual organs.

Question 34

What are the **three major body axes** that the zygote must establish after fertilization?

Answer 34

* Anteroposterior axis * Dorsoventral axis * Left-right axis

Question 35

What does the **anteroposterior axis** organize in the body?

Answer 35

It defines the **front-to-back** orientation of the body, organizing structures from the **head** (anterior) to the **tail or feet** (posterior). ## Footnote It plays a key role in patterning during embryonic development.

Question 36

What does the **dorsoventral axis** organize in the body?

Answer 36

The **top** (dorsal) and **bottom** (ventral) parts of an organism’s body. ## Footnote It plays a key role in embryonic development.

Question 37

What does the **left-right axis** organize in the body?

Answer 37

It establishes asymmetry between the **left and right sides of the body**, ## Footnote It helps to determine the proper positioning of organs such as the heart, liver, and lungs during embryonic development.

Question 38

After the formation of the three primary germ layers, what can begin in the embryo?

Answer 38

Organogenesis ## Footnote The creation of organs.

Question 39

What is **cleavage**?

Answer 39

A series of **rapid mitotic cell divisions** of the zygote that result in a **multicellular embryo**, without an increase in overall size.

Question 40

What are the **three primary germ layers** formed during early development?

Answer 40

* Ectoderm * Mesoderm * Endoderm

Question 41

# Define: endotherm

Answer 41

Animals that are capable of maintaining their internal body temperature regardless of the environmental temperature.

Question 42

# Define: ectotherm

Answer 42

Organisms that are unable to generate their own heat in reliable quantities and must rely on environmental sources to maintain their internal temperature.

Question 43

What is the primary method of **heat generation** in endothermic animals?

Answer 43

Metabolic processes ## Footnote Endothermic organisms, often described as generating "heat from within," include birds and mammals.

Question 44

How do endotherms dissipate **excess heat**?

Answer 44

Through methods such as: * sweating * panting * vasodilation ## Footnote Capillary constriction (vasoconstriction) conserves heat rather than dissipates it.

Question 45

What are some **advantages** of endothermy?

Answer 45

* Thriving in diverse environments. * Ability to keep active for lengthy periods. * Well-developed brains.

Question 46

What are some **disadvantages** of endothermy?

Answer 46

* Highly energy-intensive. * Sensitive to temperature extremes.

Question 47

How do **ectotherms** maintain their body temperature?

Answer 47

By relying on **environmental sources** and behavior methods to maintain a safe body temperature. ## Footnote Ectotherms rely on "heat from the outside." Examples include fish, crocodiles, insects, and amphibians.

Question 48

What is the purpose of **cryoprotectants** in ectotherms?

Answer 48

Prevent ice from forming in the animal's blood and tissue.

Question 49

What are some **advantages** of ectothermy?

Answer 49

* Can go longer without food. * Not as sensitive to temperature extremes.

Question 50

What are some **disadvantages** of ectothermy?

Answer 50

* Less active in cold environments limited to specific habitats. * Some ectotherms have less complex nervous systems compared to endotherms, but not all have underdeveloped brains.