B and D are not true for Karl Ernst von Baer’s principles.

This developmental biology question tests knowledge of von Baer’s laws of embryology from 1828, contrasting general-to-special progression against recapitulation theory.

Option Analysis

A. General features of a large group of animals appear earlier in development as compared to the specialized features of a smaller group: True. Von Baer’s first law states general characters (e.g., vertebrate features) form before special ones (e.g., mammalian traits).

B. General features of a large group of animals appear later in development as compared to the specialized features of a smaller group: Not true. This reverses von Baer’s first law; specialized features arise later, not earlier.

C. Early embryo of a higher animal looks like a lower animal: Not true. Von Baer’s third/fourth laws reject recapitulation; embryos diverge from general forms without resembling lower adult forms.

D. Early embryo of a higher animal looks like embryo of a lower animal: True. Von Baer’s fourth law: higher animal embryos resemble lower animal embryos, not adults (e.g., mammalian gastrula like fish gastrula).

A and C: Incorrect. A is true; C is false.
B and C: Incorrect. Both false, but answer choices specify pairs.
B and D: Correct. B is false (reversal); D is true.
A and D: Incorrect. Both true.​

Not true for Karl Ernst von Baer’s principles include misconceptions like general features appearing late or higher embryos mimicking lower adults. Von Baer’s 1828 laws describe epigenetic development from general to specific forms, foundational to comparative embryology.

Von Baer’s True Principles

Not true for Karl Ernst von Baer’s principles contrasts his four laws:

1. General features of large groups appear earlier than specialized ones (e.g., notochord before limbs).​

2. Less general forms develop from most general.​

3. Embryos separate from other forms, not pass through them.​

4. Higher embryos resemble lower embryos, not adults.​

Common Misconceptions

B reverses timing (general late, special early)—false. C implies recapitulation (higher like lower adult)—von Baer refuted this. D aligns with law 4—true.​

Exam Relevance

Mastering not true for Karl Ernst von Baer’s principles clarifies epigenesis vs. preformation, key for NEET/CSIR exams in developmental biology.​