【PEP】High School Biology, Compulsory Vol. 2: A Dream of Shade Under Rice — The Far-Reaching Significance of Genetic Research

A Dream of Shade Under Rice: From Vision to Reality

The ultimate goal of genetics is not only to unravel the mysteries of heredity, but also to reshape nature by mastering genetic laws. Taking Academician Yuan Longping's "hybrid rice" as an example, the discovery of genetic factors laid the theoretical foundation for modern breeding, turningthe "dream of shade under rice"from a scientific fantasy into a real force for ensuring global food security.

Key Scientific Pillars

Hybrid Vigor & Food SecurityCross-pollination based on genetic principles produces offspring with significantly superior growth vigor and yield compared to their parents.
Key Technical Bottleneck: Male SterilityRice has perfect flowers (both male and female organs). By finding "male sterile" plants (with defective stamens but normal pistils), efficient large-scale crossbreeding was achieved.
Logical Breakthrough: Wild AbortiveThe wild male-sterile rice discovered in 1970 was a turning point for hybrid rice, confirming the diversity of genetic factors in nature.

The Essence of Breeding

This is a profound interpretation of Mendel's laws of inheritance: by controlling the combination of genetic factors, humans can purposefully "design" the traits of organisms.

QUESTION 1

In hybrid rice production, why is it necessary to find "male sterile" plants?

To improve the nutritional value of rice

Rice is self-pollinating; male sterility eliminates the enormous labor of manual emasculation

Male sterile plants naturally have a higher yield than normal rice

Male sterile plants are more adaptable to drought conditions

QUESTION 2

What type of resource does the "Wild Abortive" discovered by Academician Yuan Longping belong to, in biological classification?

Artificially induced mutation resource

Invasive alien species

Precious natural germplasm resource

QUESTION 3

Which of the following statements about hybrid vigor is correct?

All traits of the hybrid offspring must be superior to the parents

Only crosses between homozygous individuals of the same species can produce hybrid vigor

Hybrid offspring may outperform their parents in traits such as viability and yield

QUESTION 4

Which of the following describes the characteristics of a male sterile plant?

Both stamens and pistils develop abnormally

Stamens develop normally, but pistils are abnormal

Stamens develop abnormally, but the pistil is normal

QUESTION 5

Which achievement exemplifies the leap from "basic theory" to "technological application" in genetics research?

Improvement of the microscope

The successful development of three-line hybrid rice

The discovery of photosynthesis

Comprehensive Inquiry: Pollen Identification Method to Verify Genetic Laws

Using microscopic observation to directly verify the behavior of genetic factors

In rice, non-glutinous and glutinous endosperms are a pair of contrasting traits. The starch in non-glutinous pollen is amylose, which turns blue-black when stained with iodine, while the starch in glutinous pollen is amylopectin, which turns orange-red. Now, cross pure-bred non-glutinous rice with pure-bred glutinous rice, and stain the F1 pollen with iodine solution.

1. Based on the law of segregation and the law of independent assortment, determine whether the following statements are correct: (1) The 3:1 phenotypic ratio in F2 depends on the random union of male and female gametes. (2) The law of independent assortment states that the 4 types of sperm produced by F1 randomly combine with the 4 types of eggs.

Answer:
Analysis: (1) Correct. The 3:1 ratio is based on the equal probability of gamete formation and random union during fertilization. (2) Incorrect. The essence of the law of independent assortment is that during gamete formation, non-allelic genes located on non-homologous chromosomes assort independently as homologous chromosomes separate, not the random combination during fertilization.

2. Under the microscope, half of the F1 pollen grains appear blue-black, and half appear orange-red. What does this phenomenon directly prove?

Answer:
Reference Answer: This phenomenon directly proves Mendel's law of segregation. Specifically: when F1 (heterozygotes) produce gametes through meiosis, the paired genetic factors (genes controlling non-glutinous and glutinous traits) segregate from each other and enter different gametes, resulting in two types of gametes in equal proportions (blue-black : orange-red = 1:1).

3. What are the advantages of this "pollen identification method" compared to observing the phenotypic segregation ratio in F2?

Answer:
Reference Answer: This method is more intuitive and faster. It directly reveals the behavior of genetic factors at the gamete level (haploid stage), eliminating the need for cumbersome crossbreeding experiments and waiting for the next generation to observe phenotypes, thereby shortening the time required for verifying laws and breeding identification.