Heredity - 3 - Class 10 MCQ

Only those variation which are useful and have advantage get selected.

Evolutionary Connection Between Dinosaurs and Birds

In the context of evolution, the presence of feathers in both dinosaurs and birds suggests that birds have evolved from reptiles (specifically, from a group of theropod dinosaurs). This is supported by several lines of evidence, including:

• Fossil Record: Fossil discoveries have revealed the existence of feathered dinosaurs, such as Microraptor and Archaeopteryx, which exhibit features intermediate between reptiles and birds.


• Anatomical Similarities: Birds and certain dinosaurs share numerous anatomical features, including hollow bones, wishbones, and similar skeletal structures.


• Genetic Evidence: Comparative analysis of the genetic material of birds and reptiles has provided further support for the evolutionary connection between the two groups.


• Developmental Similarities: The embryonic development of birds and reptiles shows striking similarities, suggesting a common ancestry.

Therefore, the correct answer is D: birds have evolved from reptiles. This is a widely accepted scientific consensus based on extensive research and evidence.

The information coded in DNA (genes) is for only polypeptides (proteins). Insulin hormone is peptide and all enzyme are also proteins.

Explanation:
The maleness of a child is determined by the Y chromosome in the zygote.
- The zygote is formed when the sperm (containing either an X or Y chromosome) fertilizes the egg (which contains an X chromosome).
- If the sperm carries an X chromosome, the zygote will develop into a female child (XX).
- If the sperm carries a Y chromosome, the zygote will develop into a male child (XY).
Key Points:
- The maleness of a child is determined by the presence of the Y chromosome in the zygote.
- The X chromosome alone does not determine maleness.
- The presence of the Y chromosome is necessary for the development of male characteristics.
- The sex determination is not random or by chance, but rather based on the specific combination of chromosomes present in the zygote.

During formation of gametes meiosis occurs resulting in exchange of genes by the process of crossing over.

Archaeopteryx and its Connection:


Archaeopteryx is a fossil species that lived during the Late Jurassic period, approximately 150 million years ago. It is considered to be a significant transitional fossil, providing evidence of the evolutionary link between reptiles and birds. Here is a detailed explanation of how Archaeopteryx connects these two groups:
1. Avian Characteristics:
- Archaeopteryx exhibits several avian (bird) characteristics, including feathered wings and a fused clavicle (wishbone). These features are typically associated with birds and are absent in reptiles.
- The presence of feathers suggests that Archaeopteryx was capable of flight, another characteristic unique to birds.
2. Reptilian Characteristics:
- Despite its avian features, Archaeopteryx also retains several reptilian characteristics, such as a long bony tail and clawed fingers on its wings.
- The presence of teeth in its beak-like jaws is another reptilian trait.
3. Skeletal Features:
- Archaeopteryx shares several skeletal features with both reptiles and birds. For example, its skeletal structure resembles that of small theropod dinosaurs, including a similar arrangement of bones in its hands and feet.
- This similarity suggests that Archaeopteryx evolved from a dinosaur-like reptilian ancestor.
4. Transitional Nature:
- The combination of avian and reptilian characteristics in Archaeopteryx makes it a transitional fossil, providing evidence of the evolutionary link between reptiles and birds.
- It supports the theory that birds evolved from reptiles, specifically theropod dinosaurs, over millions of years.
Conclusion:
The fossil remains of Archaeopteryx serve as an important connecting link between reptiles and birds. Its combination of avian and reptilian features provides evidence for the evolutionary transition from reptilian ancestors to modern birds. Therefore, the correct answer is B: reptiles and birds.

50% Tt Tall and 50% tt dwarf

Explanation:
The evolution of wild cabbage into new varieties like cabbage, broccoli, and cauliflower is primarily attributed to artificial selection. Here's a detailed explanation:
Artificial selection:
- In artificial selection, humans deliberately choose certain individuals with desirable traits for breeding, resulting in the selection and propagation of specific traits in subsequent generations.
- Farmers and cultivators have selectively bred wild cabbage plants over many generations to develop new varieties with larger edible leaves (cabbage), dense flower buds (broccoli), and enlarged flower clusters (cauliflower).
- By selecting and breeding plants with specific traits, humans have modified the genetic makeup of wild cabbage populations to create these new varieties.
Other options mentioned in the question are not the primary mechanisms for the evolution of wild cabbage into new varieties:
Genetic drift:
- Genetic drift refers to random changes in the frequency of genetic traits within a population due to chance events.
- While genetic drift can play a role in evolution, it is unlikely to be the primary mechanism for the development of cabbage, broccoli, and cauliflower from wild cabbage.
Natural selection:
- Natural selection involves the process by which individuals with advantageous traits are more likely to survive and reproduce, leading to the increased frequency of those traits in a population.
- While natural selection can influence the evolution of wild cabbage, it is not the main driving force behind the development of cabbage, broccoli, and cauliflower.
Reproductive isolation:
- Reproductive isolation refers to barriers that prevent individuals of different populations or species from interbreeding.
- While reproductive isolation can contribute to speciation and the evolution of new species, it is not directly responsible for the development of cabbage, broccoli, and cauliflower from wild cabbage.
In summary, the evolution of wild cabbage into new varieties like cabbage, broccoli, and cauliflower is primarily a result of artificial selection conducted by humans through selective breeding.

Explanation of the correct option: C.

1. According to the Mendel's first law of inheritance or law of dominance, the hybrid offspring produced will only inherit the dominant trait in the phenotype.
2. The alleles that are suppressed are known as recessive traits while that determines the trait are known as dominant traits.
3. A cross between a tall plant (TT) and short pea plant (tt) resulted in progeny that were all tall plants because tallness is the dominant trait.
4. Thus, tallness is the dominant trait.

Explanation:
The sex of human offspring is determined through the father's sex chromosomes. Here's a detailed explanation:
- The sex chromosomes in humans are called X and Y chromosomes. Females have two X chromosomes (XX), while males have one X and one Y chromosome (XY).
- During reproduction, the mother always contributes an X chromosome, while the father can contribute either an X or a Y chromosome.
- If the father contributes an X chromosome, the resulting combination will be XX, and the offspring will be female.
- If the father contributes a Y chromosome, the resulting combination will be XY, and the offspring will be male.
- Therefore, it is the father's sex chromosomes that determine the sex of the offspring.
Key Points:
- Human offspring's sex is determined through the father's sex chromosomes.
- Females have two X chromosomes (XX) and males have one X and one Y chromosome (XY).
- If the father contributes an X chromosome, the offspring will be female.
- If the father contributes a Y chromosome, the offspring will be male.

If a round, green seeded pea plant  is crossed with wrinkled, yellow seeded pea plant, the seeds produced in F1 generation are round and yellow.

Explanation:
The best statement that describes an organism in the context of natural selection is option C: The ability to adapt to the environment in the niche it occupies.
Here's a detailed explanation:
- Natural selection is the process by which organisms that are better adapted to their environment have a higher chance of survival and reproduction, passing on their advantageous traits to future generations.
- The term "survival of the fittest" refers to the idea that the organisms with traits that are most beneficial for their specific environment are more likely to survive and reproduce.
- The key factor in natural selection is the ability of an organism to adapt to its environment.
- Option A, which suggests that the strength of an organism compared to others of the same species determines its success, is not always the case. Adaptability is more important than physical strength.
- Option B, which mentions the ability to gather food and resources for offspring, is important for the survival of the offspring, but it does not necessarily determine the overall success of the organism in its environment.
- Option D, the number of fertile offspring an organism has, can be an indicator of reproductive success, but it does not directly address the ability to adapt to the environment.
In conclusion, the ability of an organism to adapt to the environment in the niche it occupies is the most accurate statement that describes an organism in the context of natural selection.

The sex of an individual is determined by the combination of sex chromosomes inherited from both parents. In humans, females have two X chromosomes (XX) and males have one X and one Y chromosome (XY).
When a zygote is formed, it receives one sex chromosome from each parent. If the zygote receives an X chromosome from the father, it will develop into a female. This is because females have two X chromosomes, one from each parent.
Therefore, the correct answer is:
B: Female

Concept not included in Charles Darwin's theory of Natural Selection:
Punctuated equilibrium
Explanation:
Charles Darwin's theory of Natural Selection, outlined in his book "On the Origin of Species," includes several key concepts that explain the process of evolution. However, one concept that is not included in his theory is punctuated equilibrium. Here is an explanation of the other concepts included in Darwin's theory:
1. Struggle for existence: Darwin proposed that individuals within a population compete with each other for limited resources, such as food, water, and shelter. This competition leads to a struggle for existence, where only the individuals best adapted to their environment are more likely to survive and reproduce.
2. Survival of the fittest: Darwin coined the term "survival of the fittest" to describe the idea that the individuals with the most favorable traits for their environment are more likely to survive and pass on their genes to the next generation. This process leads to the gradual accumulation of beneficial traits in a population over time.
3. Overproduction of offspring: Darwin observed that many species produce more offspring than can possibly survive to adulthood. This overproduction leads to a competition for resources and increases the chances of survival for those individuals with advantageous traits.
However, the concept of punctuated equilibrium was proposed by Stephen Jay Gould and Niles Eldredge in the 1970s as an alternative to the gradualism model of evolution. Punctuated equilibrium suggests that evolution occurs in relatively short bursts of rapid change, followed by long periods of stability or stasis. This concept focuses on the idea that species remain relatively unchanged for long periods of time, with occasional rapid bursts of evolutionary change.
In conclusion, while Charles Darwin's theory of Natural Selection includes concepts such as struggle for existence, survival of the fittest, and overproduction of offspring, the concept of punctuated equilibrium is not included in his original theory.

Human males have 23 pairs of autosomes and XY sex chromosomes.

Both natural selection and genetic drift are mechanisms for evolution. The key distinction is that in genetic drift allele frequencies change by chance, whereas in natural selection allele frequencies change by differential reproductive success and genetic drift does not involve competition between members of species.

Male produces two types of sperms 50% sperms have X chromosome and rest 50% have Y chromosome. If sperm having X chromosome fertilises ovum the sex of child will be female and in case sperm having Y chromosome fertilises the egg the child will be male.

Plant is easily grown in garden soil so it can be easily used for experiment. 
Mendels experiment is to prove that pure tall  and pure dwarf give different types of progency. So, he have to take a plant which have distinct phenotype. Therefore he used pea.

The maleness of a child is determined by:
- The Y chromosome: The presence of a Y chromosome in the child's genetic makeup is the primary factor in determining maleness. The Y chromosome contains the SRY gene, which triggers the development of male sex characteristics.
- The X chromosome: The presence of an X chromosome alone does not determine maleness. Females typically have two X chromosomes, while males have one X and one Y chromosome.
- The cytoplasm of germ cell: The cytoplasm of the germ cell, which includes the egg and sperm cells, does not directly determine the maleness of a child. The genetic information contained within the chromosomes is the determining factor.
- Sex is determined by chance: While it is true that the combination of genetic material during fertilization is a random process, the presence of a Y chromosome is necessary for the development of male characteristics. Therefore, it is not solely determined by chance.
In conclusion, the maleness of a child is primarily determined by the presence of a Y chromosome in their genetic makeup. The X chromosome, cytoplasm of germ cells, and chance also play roles in the overall process of sex determination, but the Y chromosome is the key factor.

The correct answer is A: More closely they are related and more recently they had a common ancestor.
Here's a detailed explanation:
1. Characteristics and relatedness:
- When two species share more characteristics, it indicates that they are more closely related to each other.
- These shared characteristics can be physical traits, genetic similarities, or behavioral patterns.
- Common characteristics suggest a closer evolutionary relationship between the species.
2. Common ancestors:
- The presence of shared characteristics implies that the two species had a common ancestor.
- The more characteristics they have in common, the more recently they shared a common ancestor.
- This means that they diverged from a common ancestor more recently in evolutionary history.
3. Evidence of common ancestry:
- The concept of common ancestry is supported by various lines of evidence, including fossil records, genetic analysis, and comparative anatomy.
- By examining these pieces of evidence, scientists can determine the relatedness between species and estimate the time of divergence from a common ancestor.
4. Evolving traits:
- Over time, species diverge and develop different traits through the process of evolution.
- As species evolve and adapt to different environments, they accumulate unique characteristics that differentiate them from their common ancestors and other related species.
In summary, the more characteristics two species have in common, the more closely they are related and the more recently they had a common ancestor. This understanding is based on the principles of evolution and the evidence gathered from various scientific disciplines.