Spring with Idioms 1

Spring with Idioms

Spring with Idioms 4

Spring with Idioms 2

ESL 3 Have to and need to with questions and answers Spring 2025

Seasons Spring In the spring, fresh winds blow. We plant new seeds, and green buds grow. Eggs hatch open. Little chicks sing. The sun is out. It must be spring! The grass gets wet. Splish! Splash! Splish! When we step, we hear a squish. Summer Then summer is here and it gets hot. We are not in school. We play a lot. Bugs buzz and hum. The plants grow tall. Next to them, I look small. Summer goes fast, and when it ends, we will go back to school with all our friends.

CHARACTERISTICS OF LIFE The world is filled with familiar objects, such as tables, rocks, plants, pets, and automobiles. Which of these objects are living or were once living? What are the criteria for assigning something to the living world or the nonliving world? Biologists have established that living things share seven characteristics of life. These characteristics are organization and the presence of one or more cells, response to a stimulus (plural, stimuli), homeostasis, metabolism, growth and development, reproduction, and change through time. Organization and Cells Organization is the high degree of order within an organism’s internal and external parts and in its interactions with the living world. For example, compare an owl to a rock. The rock has a spe- cific shape, but that shape is usually irregular. Furthermore, differ- ent rocks, even rocks of the same type, are likely to have different shapes and sizes. In contrast, the owl is an amazingly organized individual, as shown in Figure 1-2. Owls of the same species have the same body parts arranged in nearly the same way and interact with the environment in the same way. Copyright © by Holt, Rinehart and Winston. All rights reserved. ORGANISM (Barn Owl) ORGAN (Owl’s Ear) TISSUE (Nervous Tissue Within the Ear) CELL (Nerve Cell) Every living organism has a level of organization. The different levels of organization for a complex multicellular organism, such as an owl, are shown in the figure below. FIGURE 1-2 THE SCIENCE OF LIFE 7 All living organisms, whether made up of one cell or many cells, have some degree of organization. A cell is the smallest unit that can perform all life’s processes. Some organisms, such as bacteria, are made up of one cell and are called unicellular (YOON-uh-SEL-yoo-luhr) organisms. Other organisms, such as humans or trees, are made up of multiple cells and are called multicellular (MUHL-ti-SEL-yoo-luhr) organisms. Complex multicellular organisms have the level of orga- nization shown in Figure 1-2. In the highest level, the organism is made up of organ systems, or groups of specialized parts that carry out a certain function in the organism. For example, an owl’s ner- vous system is made up of a brain, sense organs, nerve cells, and other parts that sense and respond to the owl’s surroundings. Organ systems are made up of organs. Organs are structures that carry out specialized jobs within an organ system. An owl’s ear is an organ that allows the owl to hear. All organs are made up of tissues. Tissues are groups of cells that have similar abilities and that allow the organ to function. For example, nervous tissue in the ear allows the ear to detect sound. Tissues are made up of cells. A cell must be covered by a membrane, contain all genetic information necessary for replication, and be able to carry out all cell functions. Within each cell are organelles. Organelles are tiny structures that carry out functions necessary for the cell to stay alive. Organelles contain biological molecules, the chemical compounds that provide physical structure and that bring about movement, energy use, and other cellular functions. All biological molecules are made up of atoms. Atoms are the simplest particle of an ele- ment that retains all the properties of a certain element. Response to Stimuli Another characteristic of life is that an organism can respond to a stimulus—a physical or chemical change in the internal or external environment. For example, an owl dilates its pupils to keep the level of light entering the eye constant. Organisms must be able to respond and react to changes in their environment to stay alive. ORGANELLE (Mitochondrion) BIOLOGICAL MOLECULE (Phospholipid) ATOM (Oxygen) cell from the Latin, cella meaning “small room,” or “hut” Word Roots and Origins www.scilinks.org Topic: Characteristics of Life Keyword: HM60257 mb06se_bios01.qxd 5/18/07 10:37 AM Page 7 8 CHAPTER 1 Homeostasis All living things, from single cells to entire organisms, have mecha- nisms that allow them to maintain stable internal conditions. Without these mechanisms, organisms can die. For example, a cell’s water content is closely controlled by the taking in or releas- ing of water. A cell that takes in too much water will rupture and die. A cell that doesn’t get enough water will also shrivel and die. Homeostasis (HOH-mee-OH-STAY-sis) is the maintenance of a stable level of internal conditions even though environmental conditions are constantly changing. Organisms have regulatory systems that maintain internal conditions, such as temperature, water content, and uptake of nutrients by the cell. In fact, multi- cellular organisms usually have more than one way of maintain- ing important aspects of their internal environment. For example, an owl’s temperature is maintained at about 40°C (104°F). To keep a constant temperature, an owl’s cells burn fuel to produce body heat. In addition, an owl’s feathers can fluff up in cold weather. In this way, they trap an insulating layer of air next to the bird’s body to maintain its body temperature. Metabolism Living organisms use energy to power all the life processes, such as repair, movement, and growth. This energy use depends on metabolism (muh-TAB-uh-LIZ-uhm). Metabolism is the sum of all the chemical reactions that take in and transform energy and materials from the environment. For example, plants, algae, and some bacteria use the sun’s energy to generate sugar molecules during a process called photosynthesis. Some organisms depend on obtaining food energy from other organisms. For instance, an owl’s metabolism allows the owl to extract and modify the chemi- cals trapped in its nightly prey and use them as energy to fuel activities and growth. Growth and Development All living things grow and increase in size. Some nonliving things, such as crystals or icicles, grow by accumulating more of the same material of which they are made. In contrast, the growth of living things results from the division and enlargement of cells. Cell division is the formation of two new cells from an existing cell, as shown in Figure 1-3. In unicellular organisms, the primary change that occurs following cell division is cell enlargement. In multi- cellular life, however, organisms mature through cell division, cell enlargement, and development. Development is the process by which an organism becomes a mature adult. Development involves cell division and cell differen- tiation, or specialization. As a result of development, an adult organism is composed of many cells specialized for different func- tions, such as carrying oxygen in the blood or hearing. In fact, the human body is composed of trillions of specialized cells, all of which originated from a single cell, the fertilized egg. This unicellular organism, Escherichia coli, inhabits the human intestines. E. coli reproduces by means of cell division, during which the original cell splits into two identical offspring cells. FIGURE 1-3 Observing Homeostasis Materials 500 mL beakers (3), wax pen, tap water, thermometer, ice, hot water, goldfish, small dip net, watch or clock with a second hand Procedure 1. Use a wax pen to label three 500 mL beakers as follows: 27°C (80°F), 20°C (68°F), 10°C (50°F). Put 250 mL of tap water in each beaker. Use hot water or ice to adjust the tem- perature of the water in each beaker to match the temperature on the label. 2. Put the goldfish in the beaker of 27°C water. Record the number of times the gills move in 1 minute. 3. Move the goldfish to the beaker of 20°C water. Repeat observations. Move the goldfish to the beaker of 10°C. Repeat observations. Analysis What happens to the rate at which gills move when the temp- erature changes? Why? How do gills help fish maintain homeostasis? Quick Lab mb06se_bios01.qxd 5/18/07 10:37 AM Page 8 THE SCIENCE OF LIFE 9 Reproduction All organisms produce new organisms like themselves in a process called reproduction. Reproduction, unlike other characteristics, is not essential to the survival of an individual organism. However, because no organism lives forever, reproduction is essential for the continuation of a species. Glass frogs, as shown in Figure 1-4, lay many eggs in their lifetime. However, only a few of the frogs’ off- spring reach adulthood and successfully reproduce. During reproduction, organisms transmit hereditary informa- tion to their offspring. Hereditary information is encoded in a large molecule called deoxyribonucleic acid, or DNA. A short segment of DNA that contains the instructions for a single trait of an organism is called a gene. DNA is like a large library. It contains all the books—genes—that the cell will ever need for making all the struc- tures and chemicals necessary for life. Hereditary information is transferred to offspring during two kinds of reproduction. In sexual reproduction, hereditary information recombines from two organisms of the same species. The resulting offspring are similar but not identical to their parents. For example, a male frog’s sperm can fertilize a female’s egg and form a single fer- tilized egg cell. The fertilized egg then develops into a new frog. In asexual reproduction, hereditary information from different organisms is not combined; thus the original organism and the new organism are genetically the same. A bacterium, for example, reproduces asexually when it splits into two identical cells. Change Through Time Although individual organisms experience many changes during their lifetime, their basic genetic characteristics do not change. However, populations of living organisms evolve or change through time. The ability of populations of organisms to change over time is important for survival in a changing world. This factor is also impor- tant in explaining the diversity of life-forms we see on Earth today.

Write personal questions for a1-a2 kids after they read: Incredible Places to Stay Introduction. Do you want to see some of the world's most amazing hotels? Let's go! Sliding with Sharks. The first stop on your tour is Las Vegas, Nevada. At the Golden Nugget, you can ride a waterslide. It takes you through a shark tank. A Cool Place to Stay. The next stop is the Hôtel de Glace (O-tel DEH GLAHS) in Canada. Many parts of the hotel are made of ice. The ice melts away in the spring. Each winter, it takes a lot of work to build the hotel again. Breakfast with Giraffes. From Canada, you'll travel to Kenya. Giraffes live in the forests around a hotel called Giraffe Manor. Every morning, the giraffes come to the hotel to eat. If you stay there, you can feed them! In the Trees. The next stop on your tour is Sweden. The Treehotel is made up of many tree houses. The Mirrorcube has glass all around it. This tree house blends in with the woods. One tree house looks like a big bird's nest. The UFO tree house looks as if it is from outer space. A Room Without a View. When you are in Sweden, stop at the Sala Silvermine Hotel. When you get there, you can stay in the deepest hotel room in the world! It is a long way down to your room. Dress in warm clothes because it is very cold in the mine. Sleeping with Fish. Your last stop is Jules' Undersea Lodge in Florida. You have to swim down to reach your room! When you are ready to eat, you can even have pizza. Someone from the hotel will swim it down to you. Conclusion. It is time to go back home now. Each incredible hotel is more than just a place to stay for the night. At each one, you will have a lot of fun!

Whose Tracks Are These? Animal Visitors. How do we know whether an animal has visited a place? One way we know is because it may leave tracks, or marks in the soil. Tracks show where the animal's body has touched the ground. Let's find out who has visited us today! Large Animals. A large animal that likes honey made these tracks. This animal is a good climber. It has strong claws for digging up plants, and it eats animals, too. Can you guess who it is? A black bear made these tracks. Black bears sleep all winter and wake up hungry in the spring. A large animal with hooves made these tracks. This animal can eat ten pounds of leaves, bark, and twigs each day. Can you guess who it is? A deer made these tracks. Male deer grow antlers in the spring and shed them in late winter. Baby deer have spots that disappear when they grow up. A large, strong cat made these tracks. This hunter runs fast and jumps far. It eats other animals, such as deer. birds, and rabbits. Can you guess who it is? A mountain lion made these tracks. Adult mountain lions live alone most of the time. Babies must learn to hunt before they can leave their mothers. Small Animals. A smart bird made these tracks. It has a curved beak and sharp claws. It hunts at night and eats many kinds of animals. Can you guess who it is? An owl made these tracks. It has large yellow eyes and can see well in the dark. It makes a noise called a hoot. A small animal made these tracks. Its tail made the line between the footprints. This animal must run very fast to escape being eaten. Can you guess who it is? A mouse made these tracks. Mice are food for owls, snakes, and other animals. But this one got away! Many Kinds of Tracks. Each kind of animal has its own special tracks. Look for tracks when you are in nature. Have fun finding out who has been visiting!

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