Question

1. what is a significant impact of deforestation on ecosystems? a. disrupting habitats and reducing biodiversity b. enhancing oxygen balance c. encouraging biodiversity d. decreasing carbon dioxide levels 27. which of the following correctly describes the structure of dna? a. double - stranded helix b. single - stranded helix c. coiled structure without nucleotides d. triple - stranded helix 28. if a homozygous dominant parent (tt) is crossed with a homozygous recessive parent (tt), what will be the genotypic ratio of their offspring? a. 50% homozygous dominant (tt), 50% homozygous recessive (tt) b. 75% homozygous dominant (tt), 25% heterozygous (tt) c. 100% heterozygous (tt) d. 25% homozygous dominant (tt), 50% heterozygous (tt), 25% homozygous recessive (tt)

Explanation:

Question 26:

Deforestation destroys tree - cover, which disrupts the habitats of many species and reduces biodiversity. It does not enhance oxygen balance, encourage biodiversity, or decrease carbon dioxide levels (trees absorb CO2, and deforestation releases it).

Question 27:

DNA has a double - stranded helix structure composed of nucleotides.

Question 28:

When a homozygous dominant (TT) is crossed with a homozygous recessive (tt), all offspring will have the genotype Tt (heterozygous) according to Mendelian genetics.

Answer:

1. A. Disrupting habitats and reducing biodiversity
2. A. Double - stranded helix
3. C. 100% heterozygous (Tt)