Genotypes and Phenotypes Quiz

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Questions and Answers

What is true about homozygous genotypes?

They express a characteristic regardless of the partner gene. (correct)

They can only exist if both alleles are dominant.

They have identical alleles for a trait. (correct)

They are always associated with recessive traits.

How do recessive genes express their traits?

When paired with any version of a gene.

In any heterozygous situation.

Only when paired with a similar version of a gene. (correct)

Dominating a phenotype over a dominant gene.

What is the fate of recessive gene carriers?

They will always express the recessive traits.

They can pass on the trait regardless of expression. (correct)

They may express traits only under specific conditions.

They are unaffected by the recessive trait. (correct)

What distinguishes dizygotic twins from monozygotic twins?

Dizygotic twins share genetic material as average siblings. Signup and view all the answers

What type of genetic disorders are most commonly known?

Dominant gene-linked disorders. Signup and view all the answers

In which group are males more at risk for sex-linked disorders?

Due to having one X chromosome. Signup and view all the answers

Which of these traits typically result from polygenic inheritance?

Skin color. Signup and view all the answers

What characterizes incomplete dominance in genetics?

Both alleles influence the phenotype, resulting in a blended effect. Signup and view all the answers

What is the most common cause of chromosomal abnormalities?

Maternal age Signup and view all the answers

Which of the following features is commonly associated with Down syndrome?

Short fingers and toes Signup and view all the answers

What genetic disorder results from an extra X chromosome in males?

Klinefelter Syndrome Signup and view all the answers

What is Patau syndrome caused by?

An extra chromosome 13 Signup and view all the answers

What is a characteristic of Edwards syndrome?

Small body size and heart defects Signup and view all the answers

Which service assists individuals in testing for and understanding potential genetic conditions?

Genetic counseling Signup and view all the answers

What is NOT a factor that may indicate a risk for genetic conditions?

Height of the parents Signup and view all the answers

Which statement about behavioral genetics is accurate?

It studies the interplay between genetics and environment. Signup and view all the answers

What does the inner group of cells in the blastocyst develop into?

The embryo Signup and view all the answers

What is the primary role of the trophoblast in prenatal development?

To nourish the developing organism Signup and view all the answers

At what stage is the multi-cellular organism referred to as an embryo?

After implantation Signup and view all the answers

What two major directions characterize growth during prenatal development?

Cephalocaudal and proximodistal Signup and view all the answers

What is the weight of the fetus approximately at the end of the second trimester?

500 grams Signup and view all the answers

During which gestational week does prenatal brain development begin?

Third gestational week Signup and view all the answers

At what point during prenatal development does the age of viability occur?

At 24 weeks Signup and view all the answers

What does the open region in the center of the neural tube form?

The brain's ventricles and spinal canal Signup and view all the answers

What is neurogenesis primarily characterized by?

The differentiation and formation of neurons. Signup and view all the answers

What do the regions of the brain that contain cell bodies resemble in appearance?

Gray matter as they appear gray. Signup and view all the answers

What characterizes passive genotype-environment correlation?

Children inherit genes and environments from their family. Signup and view all the answers

What is a major factor influencing the effects of teratogens on prenatal development?

The number of teratogens the fetus is exposed to. Signup and view all the answers

Which of the following describes an active genotype-environment correlation?

Individuals actively seek out environments that fit their genetic traits. Signup and view all the answers

At what point during pregnancy is alcohol consumption most harmful to fetal development?

At any point during pregnancy. Signup and view all the answers

What is meant by genotype-environment interactions?

Environmental influences can affect how genes express traits. Signup and view all the answers

Which condition is associated with alcohol consumption during pregnancy?

Fetal Alcohol Spectrum Disorders (FASD). Signup and view all the answers

In which period does the germinal period occur?

From conception to implantation of the zygote. Signup and view all the answers

What role do teratogens play in prenatal development?

They can cause birth defects and affect fetal development. Signup and view all the answers

What is the function of myelin in neural pathways?

To enable faster neural transmission. Signup and view all the answers

What defines epigenetics in the context of genetics?

It studies how gene expression is influenced by environmental factors. Signup and view all the answers

Which gender is known to experience greater teratogenic damage?

Males due to genetic predispositions. Signup and view all the answers

What is a zygote?

The combined genetic material from both parents at conception. Signup and view all the answers

What outcome can result from tobacco exposure during pregnancy?

Higher likelihood of preterm birth. Signup and view all the answers

Which of the following describes evoactive genotype-environment correlation?

Social reactions to individuals are based on their inherited traits. Signup and view all the answers

Study Notes

Genotypes: Homozygous and Heterozygous

Homozygous genotype displays a specific characteristic consistently.
Heterozygous genotype reveals varying dominance among genes.

Phenotypes

Dominant genes express themselves in the phenotype even when paired with recessive genes.
Recessive genes express only when homologous (similar version) is present.
Genes have different versions called alleles.
Common recessive traits include red hair, facial dimples, curly hair, normal vision, and dark hair.
Many traits are polygenic, influenced by multiple genes.
Incomplete dominance occurs when a dominant gene does not completely suppress a recessive gene.
Carriers of recessive traits inherit only one recessive gene and remain unaffected.

Heredity: Monozygotic and Dizygotic Twins

Monozygotic (identical) twins result from the splitting of a single fertilized egg, sharing the same genotype and often similar phenotypes.
About one-third of twins are monozygotic.
Dizygotic (fraternal) twins arise from two separate eggs fertilized by different sperm, sharing similar genetic material as siblings born at different times.

Heredity: Genetic Disorders

Most known genetic disorders are linked to dominant genes, but they typically do not lead to serious health issues.
Sex-linked disorders often appear due to genes located on the X chromosome, affecting males more severely.
Common sex-linked disorders include hemophilia, color blindness, and baldness.
Females require two recessive genes on both X chromosomes to express these disorders, while dominant ones can affect them equally.

Heredity: Chromosomal Abnormalities

Chromosomal abnormalities occur when a child has too many or too few chromosomes, often linked to maternal age.
Trisomy 21 (Down syndrome) involves three copies of chromosome 21, resulting in intellectual disabilities and specific physical traits.
Trisomy 13 (Patau syndrome) is characterized by extra genetic material from chromosome 13 causing various physical and intellectual issues.
Trisomy 18 (Edwards syndrome) leads to severe developmental issues and is often associated with small size and heart defects.

Heredity: Chromosomal Disorders

Turner Syndrome affects females, resulting from the loss of all or part of one X chromosome.
Klinefelter Syndrome occurs in males who have an extra X chromosome.

Heredity: Genetic Counseling

Genetic counseling helps individuals identify and understand genetic conditions affecting them or their offspring.
Factors considered include family history, ethnicity, genetic testing results, and parental health issues.

Heredity: Behavioral Genetics

This field studies how genetic and environmental factors influence behavior, suggesting a bidirectional influence.
Genotype-environment correlations types:
- Passive: Children inherit both genes and environments from their family.
- Evocative: Social environments react to individuals based on genetic traits.
- Active: Individuals seek environments supporting their genetic tendencies (niche picking).

Heredity: Genetic-Environment Interactions

Different genetic makeups can respond distinctively to environmental conditions, explaining variability in traits and disease risks.
Epigenetics studies how gene activity is regulated without changing DNA sequences, influenced by environmental factors, potentially affecting future generations.

Prenatal Development: Germinal Period

The germinal period lasts about 14 days from conception to implantation.
Zygote formation combines genetic material from both parents; blastocyst consists of inner (embryonic disk) and outer cells (trophoblast).
Approximately 50-75% of blastocysts fail to implant, with many zygotes not surviving the first two weeks.

Prenatal Development: Embryonic Period

After implantation, the organism is termed an embryo, with a placenta forming to provide nourishment.
Two primary growth directions are:
- Cephalocaudal development (head to tail).
- Proximodistal development (midline outward).
An embryo measures about an inch and weighs around 8 grams by the end of eight weeks.

Prenatal Development: Fetal Period

The phase from the ninth week until birth, with the organism called a fetus.
A fetus grows significantly, being about 3 inches and 28 grams by this stage.
The age of viability, when survival outside the womb is possible, occurs around 24 weeks.

Prenatal Development: Prenatal Brain Development

Begins in the third gestational week with stem cell differentiation into brain cells.
The neural plate forms the neural groove and then the neural tube.
By week eight, the neural tube differentiates into forebrain, midbrain, and hindbrain.
Neurogenesis is completed after five months, with neural migration primarily finished by 24 weeks.

Teratogens

Teratology studies factors causing birth defects; teratogens are environmental agents impacting fetal development.
Influencing factors for prenatal risks include timing and amount of exposure, number of teratogens, genetic makeup, and the sex of the fetus.
Alcohol consumption during pregnancy can result in lifelong cognitive and behavioral difficulties, categorized under Fetal Alcohol Spectrum Disorders (FASD).
Tobacco exposure is another significant teratogen; over 7% of pregnant women reported smoking in 2016, affecting fetal development and health.

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Description

Test your knowledge on genotypes, phenotypes, and heredity! This quiz covers key concepts such as homozygous and heterozygous characteristics, dominant and recessive genes, and the implications of monozygotic and dizygotic twins. Delve into the complexities of genetic traits and their expressions.