Apps S2 week 1 review

Aphids are a common pest that feed on tomato plants. However, some tomato plants contain a gene which produces a toxin, providing the plants with resistance to aphids. What is the most likely cause of this resistance?

• Crossing over during prophase I

• Mutation

• Independent assortment of chromosomes during metaphase I

• Sexual reproduction

What can be defined as 'The observable characteristics of an organism that depend on the genotype & the environment'?

• Genome

• Genotype

• Phenotype

• Gene pool

What can be defined as 'all of the organisms of one species that live in a habitat'?

• Community

• Population

• Species

• Genome

What can be defined as 'the total number of all alleles of all genes of all individuals within a population at a given time'?

• Gene pool

• Genome

• Genotype

• Phenotype

A cell that contains one set of chromosomes is called?

• Diploid

• Haploid

• Somatic

• Germ line

Which of these is not a cause of variation within a species?

• Mutations

• Meiosis

• Mitosis

• The environment

Answer explanation

Variation within a species (intraspecific variation) can be caused by mutations, meiosis, random fertilisation or the environment. Mitosis produces cells (or organisms) that are genetically identical.

What is the correct equation to show the effect that genes and the environment have on the phenotype of an organism?

• 
• 
• 

Answer explanation

Which of the following statements do NOT apply when phenotypic differences are qualitative?

• The differences fall into distinct categories with no intermediates

• Variation is discontinuous

• Variation would show a bell shaped curve on a graph

• Variation is continuous

Which of the following statements do NOT apply when phenotypic differences are quantitative?

• The differences do not fall into distinct categories with no intermediates

• Variation is discontinuous

• Variation would show a bell shaped curve on a graph

• Variation is continuous

If variation is mainly due to genetic factors with the environment having little influence on the phenotype, it is usually controlled by a single gene. True or false?

• True

• False