Animal Evolution

Question 1

Hox Genes

Answer 1

A group of related genes that control the body plan of an embryo along the head-tail axis, determining the identity and positioning of body structures

Question 2

Importance of Master Control Genes in Evolution

Answer 2

Master control genes regulate other genes dictating body plans and have played a crucial role in ensuring proper organism development

Question 3

Hox Genes in Mice and Fruit Flies

Answer 3

Similar in structure but evolved to function differently. Both mice and fruit flies share Hox genes that guide body development

Question 4

Common Gene Pool Between Mice and Fruit Flies

Answer 4

Mice and fruit flies shared a common gene pool around 500-600 million years ago, during early animal evolution

Question 5

Hox Genes of Frogs, Humans, and Starfish

Answer 5

Frogs, humans, and starfish possess Hox genes, but their arrangement and expression patterns differ due to evolutionary divergence

Question 6

Master Control Genes for Eye Development in Mice and Fruit Flies

Answer 6

Master control genes from a mouse will not build a fly’s eye accurately, as these genes produce species-specific structures and developmental pathways differ

Question 7

Bmp-4 in Vertebrates

Answer 7

A proteins involved in bone and cartilage development, crucial for tissue differentiation in vertebrates

Question 8

Lancelets

Answer 8

Invertebrates resembling the common ancestor of vertebrates, providing genetic and evolutionary clues to vertebrate evolution

Question 9

Precambrian Environmental Factors

Answer 9

Low atmospheric oxygen levels likely prevented the evolution of large, active animals during this period

Question 10

Cambrian Explosion

Answer 10

A period around 540 million years ago marked by rapid diversification, leading to the emergence of most major animal groups

Question 11

Environmental Changes Leading to Cambrian Explosion

Answer 11

Increased oxygen levels and the end of glaciation contributed to conditions favorable for the Cambrian explosion around 700 million years ago

Question 12

Evolutionary Mechanisms and Optimal Design

Answer 12

Evolutionary mechanisms work with pre-existing structures, leading to suboptimal designs rather than ideal anatomical forms

Question 13

Human Eye Imperfections

Answer 13

The human eye has an inverted retina, a blind spot, and is prone to retinal detachment, imperfections that reflect the evolutionary process

Question 14

Flaws in Vertebrate Eye Structure

Answer 14

Flaws in eye structure arose from the evolutionary lineage of vertebrates, where adaptions were incremental and not designed for perfection

Question 15

Vertebrate Evolution 360 Million Years Ago

Answer 15

Vertebrates developed limbs around 360 million years ago, allowing for movement on land, a key milestone in tetrapod evolution

Question 16

Acanthostega

Answer 16

A 360-million-year-old fossil fish with legs, providing evidence that legs evolved before land

Question 17

Importance of Acanthostega Fossil

Answer 17

Acanthostega offers insight into the transition from water to land by showing that legs evolved in aquatic environments

Question 18

Environment Where Tetrapods Evolved

Answer 18

The basic tetrapod body plan evolved in shallow water, where limbs helped navigation through debris-filled environments

Question 19

Exaptation

Answer 19

The process by which a trait evolves for one function but is later repurposed for another. Examples include feathers for thermoregulation, legs in water, and lungs in fish

Question 20

Closest Living Relative of Whales

Answer 20

The hippopotamus is the closest living relative of whales. Whales are classified as mammals because they breathe air, have mammary glands, and are warm-blooded

Question 21

Basilosaurus

Answer 21

An ancient whale with elongated bodies and vestigial limbs, showcasing the transition from land to sea in whale evolution

Question 22

Significance of Basilosaurus Fossils

Answer 22

Basilosaurus fossils reveal intermediate stages in whale evolution, particularly hind limbs and elongated bodies, illustrating the transition to aquatic life

Question 23

Historical Constraints of Evolution

Answer 23

Evolution is limited by random mutations and the inherited traits of an organism’s ancestors. This results in evolutionary compromises, such as vestigial traits and constrained adaptations

Question 24

Eye Anatomy and Physiology

Answer 24

The eye consists of the sclera, choroid, and retina, which work together to detect light and transmit visual signals. Light must pass through several layers before reaching the photoreceptors, which causes some imperfections in vision

Question 25

Physiology of Melanocytes

Answer 25

Melanocytes are specialized cells in the epidermis that produce melanin. Melanin protects the skin from UV radiation and influences skin color, playing a key roles in UV protection

Question 26

Vitamin D and Folic Acid

Answer 26

Sunlight affects vitamin D production and folic acid levels in the body. Vitamin D helps with calcium absorption and bone strength, while folic acid is vital for DNA synthesis and fetal development

Question 27

Evolution of Dark Skin in Humans

Answer 27

Darker skin evolved in regions with high sunlight to protect against UV radiation, which can damage DNA and deplete folic acid, leading to reproductive issues

Question 28

Evolution of Light Skin in Humans

Answer 28

Lighter skin evolved in regions with less sunlight to boost vitamin D synthesis. Light skin allows for more efficient absorption of UV rays in low-UV environments