Find the best tutors and institutes for Class 12 Tuition
Q16:
Mention any two autosomal genetic disorders with their symptoms.
Solution :
Step 1: Classification of Autosomal Genetic Disorders
Autosomal genetic disorders are clinical conditions caused by mutations in genes located on autosomes (chromosomes 1-22 in humans). Unlike sex-linked disorders, these affect males and females with equal probability [Per Mendelian Inheritance patterns]. The two primary categories include Autosomal Recessive and Autosomal Dominant disorders.
Step 2: Analysis of Phenylketonuria (Autosomal Recessive)
Phenylketonuria (PKU) is an inborn error of metabolism caused by a mutation in the gene encoding the enzyme phenylalanine hydroxylase, which is responsible for converting the amino acid phenylalanine into tyrosine. Due to this deficiency, phenylalanine accumulates in the body and is converted into phenylpyruvic acid and other derivatives.
- Genetics: Autosomal recessive inheritance [By the Law of Segregation, the phenotype manifests only in the homozygous recessive condition, $aa$].
- Clinical Symptoms:
- Severe mental retardation due to the accumulation of phenylalanine in the brain.
- Reduction in hair and skin pigmentation (melanin synthesis requires tyrosine).
- Excretion of phenylalanine in urine due to poor absorption by the kidneys.
Step 3: Analysis of Myotonic Dystrophy (Autosomal Dominant)
Myotonic Dystrophy is a multisystem disorder characterized by the inability of muscles to relax after contraction. It is caused by an expansion of a trinucleotide repeat ($CTG$) in the $DMPK$ gene on chromosome 19.
- Genetics: Autosomal dominant inheritance [By the Principle of Dominance, a single mutant allele ($Aa$) is sufficient to produce the disease phenotype].
- Clinical Symptoms:
- Myotonia: Sustained muscle contraction and delayed relaxation after voluntary movement.
- Muscle Wasting: Progressive weakness and atrophy, particularly in the face, neck, and distal limb muscles.
- Systemic Complications: Cataracts, cardiac conduction abnormalities, and endocrine dysfunction.
Step 4: Comparative Summary Table
| Disorder | Inheritance Pattern | Primary Symptom |
|---|---|---|
| Phenylketonuria | Autosomal Recessive | Mental retardation; skin/hair hypopigmentation. |
| Myotonic Dystrophy | Autosomal Dominant | Muscle weakness; delayed muscle relaxation. |
Visual Representation of Autosomal Pedigree Logic
The schematic illustrates the transmission of an autosomal recessive trait where two heterozygous parents have a 25% probability of producing an affected child.
Final Solution: The two autosomal genetic disorders are Phenylketonuria (characterized by mental impairment and hypopigmentation due to enzyme deficiency) and Myotonic Dystrophy (characterized by progressive muscle weakness and delayed relaxation).
More Questions from Class 12 Biology Principles of Inheritance and Variation EXERCISES
- Q1: Mention the advantages of selecting pea plant for experiment by Mendel.
- Q1: Mention the advantages of selecting pea plant for experiment by Mendel.
- Q2(a): Differentiate between the following – (a) Dominance and Recessive
- Q2(a): Differentiate between the following – (a) Dominance and Recessive
- Q2(b): Differentiate between the following – (b) Homozygous and Heterozygous
- Q2(b): Differentiate between the following – (b) Homozygous and Heterozygous
- Q2(c): Differentiate between the following – (c) Monohybrid and Dihybrid.
- Q2(c): Differentiate between the following – (c) Monohybrid and Dihybrid.
- Q3: A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced?
- Q3: A diploid organism is heterozygous for 4 loci, how many types of gametes can be produced?
- Q4: Explain the Law of Dominance using a monohybrid cross.
- Q4: Explain the Law of Dominance using a monohybrid cross.
- Q5: Define and design a test-cross.
- Q5: Define and design a test-cross.
- Q6: Using a Punnett Square, workout the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.
- Q6: Using a Punnett Square, workout the distribution of phenotypic features in the first filial generation after a cross between a homozygous female and a heterozygous male for a single locus.
- Q7(a): When a cross in made between tall plant with yellow seeds (\(TtYy\)) and tall plant with green seed (\(Ttyy\)), what proportions of phenotype in the offspring could be expected to be (a) tall and green.
- Q7(a): When a cross in made between tall plant with yellow seeds ((TtYy)) and tall plant with green seed ((Ttyy)), what proportions of phenotype in the offspring could be expected to be (a) tall and green.
- Q7(b): When a cross in made between tall plant with yellow seeds (\(TtYy\)) and tall plant with green seed (\(Ttyy\)), what proportions of phenotype in the offspring could be expected to be (b) dwarf and green.
- Q7(b): When a cross in made between tall plant with yellow seeds ((TtYy)) and tall plant with green seed ((Ttyy)), what proportions of phenotype in the offspring could be expected to be (b) dwarf and green.
- Q8: Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in \(F_{1}\) generation for a dibybrid cross?
- Q8: Two heterozygous parents are crossed. If the two loci are linked what would be the distribution of phenotypic features in (F_{1}) generation for a dibybrid cross?
- Q9: Briefly mention the contribution of T.H. Morgan in genetics.
- Q9: Briefly mention the contribution of T.H. Morgan in genetics.
- Q10: What is pedigree analysis? Suggest how such an analysis, can be useful.
- Q10: What is pedigree analysis? Suggest how such an analysis, can be useful.
- Q11: How is sex determined in human beings?
- Q11: How is sex determined in human beings?
- Q12: A child has blood group O. If the father has blood group A and mother blood group B, work out the genotypes of the parents and the possible genotypes of the other offsprings.
- Q12: A child has blood group O. If the father has blood group A and mother blood group B, work out the genotypes of the parents and the possible genotypes of the other offsprings.
- Q13(a): Explain the following terms with example (a) Co-dominance
- Q13(a): Explain the following terms with example (a) Co-dominance
- Q13(b): Explain the following terms with example (b) Incomplete dominance
- Q13(b): Explain the following terms with example (b) Incomplete dominance
- Q14: What is point mutation? Give one example.
- Q14: What is point mutation? Give one example.
- Q15: Who had proposed the chromosomal theory of the inheritance?
- Q15: Who had proposed the chromosomal theory of the inheritance?
- Q16: Mention any two autosomal genetic disorders with their symptoms.
CBSE Solutions for Class 12 Biology Principles of Inheritance and Variation
Chapters in CBSE - Class 12 Biology
- Reproduction in Organisms
- Human Reproduction
- Reproductive Health
- Molecular Basis of Inheritance
- Evolution
- Human Health and Disease
- Strategies for Enhancement in Food Production
- Microbes in Human Welfare
- Biotechnology: Principles and Processes
- Biotechnology and Its Applications
- Organisms and Populations
- Ecosystem
- Biodiversity and Conservation
- Environmental Issues
Top Tutors who teach Principles of Inheritance and Variation
Top Tutor
C V Raman Nagar Viswa Vihar, Bangalore
20 yrs of
Exp
4 students
312 hrs of classes completed
1600
per hour
Online Classes
Education can not be forced onto a student. Teaching, more than imparting knowledge, is inspiring a change. Learning, more than just reading or memorising facts, is gaining knowledge or acquiring skills by studying. My way of teaching is conceptual, analytical, simplified and problem solving. Having worked as HOD for engineering college, I also counsel students in the areas of career development and motivation towards achieving their goals. I mentored several students to achieve good results in academic and competitive exams. I worked as a professor of Physics for Engineering college for 30 years and now taking online classes since 2018. I can teach Physics and Chemistry for 10th, 11th, 12th, UG and physics for all. Currently taking online tuitions for US, Canada and Indian students in Physics and Organic chemistry My students from US are from Heritage High School, Frisco, Texas;University of Dallas, Texas, University of Wisconsin, and Simon Fraser University, B. C. Canada.
Dr Mamatha is an extremely patient and diligent teacher. She broke down each concept in simple terms and helped me understand it in the easiest way possible. She was always willing to teach me again in case I stumbled or faced difficulty in any concept. I really started to understand physics beyond the textbook and approach the concepts in an informed way, after taking classes with her!
Top Tutor
Ottapalam, Ottapalam
8 yrs of
Exp
2 students
17 hrs of classes completed
600
per hour
Online Classes
I have 8 years of teaching experience in NEET and JEE Classes are taken with extra care
Top Tutor
Saubhagya City Road, Nijampur Malhaur
15 yrs of
Exp
1 student
12 hrs of classes completed
1200
per hour
Online Classes
Student's Home
Tutor's home
Teaching experience 12 year Mentor in goal patna Oasis patna branch Career point Lucknow Pie education Lucknow Brilliant institute Lucknow
Top Tutor
Beta I Block E, Noida
5 yrs of
Exp
1 student
500
per hour
Online Classes
Student's Home
Tutor's home
Dear Parents and students, I am Amit, We provide home-based tuition for subjects and we also do professional coaching for NEET/IIT-JEE and other competitive exams. We have experienced tutors in all the fields and subjects. We also provide demo class free of cost. We do online as well as offline mode of teaching...
Here is good faculty and they care student and student get more than 80% marks so my opinion is that first you should visit here.
Top Tutor
Malleshpalya, Bangalore
12 yrs of
Exp
2 students
17 hrs of classes completed
200
per hour
Online Classes
Have been taking classes since 2005 in bangalore for physics and maths for xi,neet,jee mains,thanks.
Other Subjects in CBSE - Class 12
Download free CBSE - Class 12 Biology Principles of Inheritance and Variation EXERCISES worksheets
Download Now
