Describe how eukaryotic cells are able to keep such large amounts of DNA in the small volume of the cell nucleus. (Hint Review the structure of a chromosome in Chapter 10.)

What is the energy of the $\alpha$ particle emitted in the decay ${ }^{2104} \mathrm{Po} \rightarrow{ }^{206} \mathrm{~Pb}+\alpha$ ? Take into account the recoil of the daughter nucleus.

Match each term on the left with its meaning on the right.

$$\begin{aligned} \text{inferior (caudal)}\qquad \qquad \qquad\quad & \text{a. pertaining to the sole of the foot}\\ &\text{b. tail bone}\\ &\text{c. ventral cavity that contains heart, lungs, and associated structures}\\ &\text{d. toward the surface of the body (external)}\\ &\text{e. lying horizontal with face downward}\\ &\text{f. turning outward}\\ &\text{g. nearer to the center (trunk of the body)}\\ &\text{h. ventral cavity that contains digestive, reproductive, and excretory structures}\\ &\text{i. turning inward or inside out}\\ &\text{j. part of the spine known as the neck}\\ &\text{k. movement toward the median plane}\\ &\text{l. away from the head; toward the tail or lower part of a structure}\\ &\text{m. away from the surface of the body (internal)}\\ &\text{n. part of the spine known as the loin}\\ &\text{o. near the back of the body}\\ \end{aligned}$$

What is the electric potential energy of a system that consists of two protons $2.5 \times 10^{-15} \mathrm{m}$ apart-as might occur inside a typical nucleus?

If the DNA of this bacterium is 4 million base pairs in length, how many total molecules of A, T, C, and G are required for replication to be successful? A 2 million C 8 million B 4 million D 32 million

Which of the following forces is (most) crucial for holding a nucleus together?

(a) electric force

(b) magnetic force

(c) the strong force

(d) friction

(e) gravity

Calculate the nuclear binding energy of the nucleus ${ }_{11}^{23} \mathrm{Na}$. The measured atomic mass of $\frac{23}{11} \mathrm{Na}$ is $22.989767$ amu.

Near the surface of the nucleus of a lead atom, the electric field has a strength of $3.4 \times 10^{21} \mathrm{~V} / \mathrm{m}$. What is the energy density in this field?

Find the energy to remove (a) one proton and (b) one neutron from a ${ }^{32} \mathrm{~S}$ nucleus. (c) Explain the difference between your answers to parts (a) and (b).

A nucleus with mass number $A=182$ and atomic number $Z=74$ loses two neutrons. What are the resulting (a) mass number, (b) atomic number, and ( c) neutron number?

In a helium atom, which contains two electrons, do you think that on average the electrons are closer to the nucleus or farther away than in a hydrogen atom? Why?

Calculate the mass defect for the neon-20 nucleus. The mass of neon-20 is $19.992440 ~u$. (Hint: How many protons and neutrons does neon-20 have?)

Match each term on the left with its meaning on the right.

$$\begin{aligned} \text{plantar}\qquad \qquad \qquad\quad & \text{a. pertaining to the sole of the foot}\\ &\text{b. tail bone}\\ &\text{c. ventral cavity that contains heart, lungs, and associated structures}\\ &\text{d. toward the surface of the body (external)}\\ &\text{e. lying horizontal with face downward}\\ &\text{f. turning outward}\\ &\text{g. nearer to the center (trunk of the body)}\\ &\text{h. ventral cavity that contains digestive, reproductive, and excretory structures}\\ &\text{i. turning inward or inside out}\\ &\text{j. part of the spine known as the neck}\\ &\text{k. movement toward the median plane}\\ &\text{l. away from the head; toward the tail or lower part of a structure}\\ &\text{m. away from the surface of the body (internal)}\\ &\text{n. part of the spine known as the loin}\\ &\text{o. near the back of the body}\\ \end{aligned}$$

Describe how eukaryotic cells are able to keep such large amounts of DNA in the small volume of the cell nucleus.