IB Biology-Mixed Questions-Core-3

A cell contains chloroplasts, plasma membrane and 80S ribosomes. What type of cell could it be?

• Bryophyte

• Lymphocyte

• Prokaryote

• Neuron

What is the minimum number of nucleotides needed to code for a polypeptide composed of 210 amino acids?

• 70

• 210

• 420

• 630

Chromosome numbers vary between species. Which statement refers to humans?

• An egg cell has 22 autosomes.

• A sperm cell has 23 autosomes.

• An egg cell has two X chromosomes.

• A zygote has two autosomes.

What is produced by meiosis in a cell of a male animal?

• Four gametes, each with the same number of chromosomes

• Two gametes, each with the same number of chromosomes

• Four gametes, each with different numbers of chromosomes

• Two gametes, each with different numbers of chromosomes

What is a community?

• A group of individuals of the same species in a given area

• A group of animals that interact socially

• A group of organisms interacting with the abiotic environment

• A group of populations interacting with each other within a given area

Mammals, birds and reptiles have an embryonic tail that may disappear during development.

What is the most likely explanation?

• Mammals have lost their tail by evolution.

• All vertebrates have a common ancestor.

• Mammals, birds and reptiles are identical when they are embryos.

• Some physical similarities of vertebrates are analogous.

Which process describes starch metabolism in humans?

• . Starch is digested by amylase in the mouth, stomach and small intestine.

• Amylase digests starch into monomers of sucrose.

• Glucose produced by the digestion of starch can be stored as glycogen.

• Optimal activity of amylase occurs in the stomach at pH 2.

Leptin helps to regulate body mass in humans and mice.

(Obese mouse (O) and a normal mouse (N))

What hypothesis could account for the differences between the mice?

• The hypothalamus of mouse O stopped producing leptin.

• Adipose cells of mouse O are continuously producing leptin.

• Mouse N has a defective leptin receptor.

• Leptin binds to receptors in the hypothalamus of mouse N.

What are linked by hydrogen bonds?

• Hydrogen and oxygen within a water molecule

• Phosphate and sugar within a DNA molecule

• Base and sugar between DNA nucleotides

• Hydrogen and oxygen in different water molecules

A molecule of DNA is found to contain 200 guanine bases, representing 25 % of the total number of bases. How many phosphate groups does this molecule of DNA contain?

• 50

• 200

• 800

• 1000