Question

1-15 The _______  is made up of two concentric membranes and is continuous with the membrane of the endoplasmic reticulum.

(a)plasma membrane

(b) Golgi network

(c)mitochondrial membrane

(d)nuclear envelope

1-16 The nucleus, an organelle found in cucaryotic cells, confines the _______ keeping them separated from other components of the cell.

(a)lysosomes

(b)chromosomes

(c)peroxisomes

(d)ribosomes.

1-17 Which of the following organelles has both an outer and an inner membrane?

(a) endoplasmic reticulum

(b) mitochondrion

(c) Iysosome

(d) peroxisomo

1-18 You fertilize cgg cells from a healthy plant with pollen (which contains the male germ cells) that has been treated with DNA-damaging agents. You find that some of the oftspring have defective chloroplasts, and that this characteristic can be passed on to future generations. This surprises you at first because you happen to know that the male germ cell in the pollen grain contributes no chloroplasts to the fertilized egg cell and thus to the offspring. What can you deduce from these results?

1-19 Mitochondria contain their own genome, are able to duplicate, and actually divide on a different timeline from the rest of the cell. Nevertheless, mitochondria cannot function for long when isolated from the cell because they are

(a)viruses.

(b)parasites.

(c)endosymbionts.

(d)anaerobes.

Answer 1

15. D

Nuclear envelope is made up of two concentric membranes. These membranes are fused at regular intervals to form a nuclear pore complex or NPC. NPC is the area through which the transport of molecules across the nucleus takes place. The outer nuclear membrane is continuous with ER and contains ribosomes. The space between two membranes is called perinuclear space.

16. B

Eukaryotes are differentiated from prokaryotes based on the nucleus. In the former, there is a well-defined nucleus that contains DNA and associated proteins, whereas in the latter, DNA is present in the cytoplasm only, in a condensed region, which is also called a nucleoid.

17. B

ER has one membrane.

Mitochondria, chloroplast, and nucleus have two membranes.

Lysosomes and peroxisomes have one membrane.

18. DNA of the male plant was defective, and chloroplast in the progeny was defective. Chloroplast is donated by the female parent. We know this information. So, we can conclude that some of the genes for chloroplast function are located on the nucleus; that's why, when one normal gene from a female parent and one abnormal gene from a male parent combined, it resulted in the formation of an abnormal chloroplast.

19. C

As per the endosymbiotic theory, prokaryotes capable of aerobic respiration started living inside a eukaryotic cell in a symbiotic association. With the course of evolution, this prokaryote became mitochondria with its DNA and ribosomes.