1.1 Which ONE of the following is a reproductive isolating mechanism?
A. Breeding at the same time of the year
B. Same courtship behaviour
C. Fertile offspring
D. Adaptation to different pollinators
1.2 Which ONE of the following is a source of variation?
A. Mitosis
B. Cloning
C. DNA replication
D. Crossing over
1.3 Scientists can develop crops that are pest resistant through the process of ...
A. Reproductive isolation
B. Artificial selection
C. Speciation
D. Natural selection
Answer (2)
The answers to the multiple-choice questions are: 1.1 D. Adaptation to different pollinators, 1.2 D. Crossing over, and 1.3 B. Artificial selection. These concepts highlight mechanisms of reproductive isolation, sources of genetic variation, and methods of crop improvement. Understanding these ideas is essential for grasping the principles of biology and evolution.
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1.1 The correct option for a reproductive isolating mechanism is D. Adaptation to different pollinators . Reproductive isolating mechanisms are features of organisms that prevent interbreeding between different species. These can be prezygotic, occurring before fertilization, or postzygotic, occurring after fertilization. In this case, adaptation to different pollinators can prevent the cross-pollination and hence interbreeding between different plant species, effectively isolating them reproductively.
1.2 The correct source of variation is D. Crossing over . Genetic variation is essential for the evolution and adaptation of species. Crossing over occurs during meiosis, the process by which gametes (egg and sperm) are formed. It is the exchange of genetic material between homologous chromosomes, leading to new combinations of genes, and thus, genetic diversity. Mitosis, cloning, and regular DNA replication do not introduce variation as they produce identical cells or copies of DNA.
1.3 Scientists can develop pest-resistant crops through the process of B. Artificial selection . Artificial selection, also known as selective breeding, is the intentional breeding of plants or animals for desired traits, in this case, pest resistance. Unlike natural selection, where environmental factors determine which individuals survive to reproduce, artificial selection is guided by humans to ensure desirable characteristics are passed on to future generations.
