CHAPTER 2 LESSON 1 REPRODUCTION WHERE DO LIVING THINGS COME FROM? • Living things come from other living things. • Every organism comes from a parent organism through the process of reproduction. REPRODUCTION • Reproduction involves the transfer of genetic material from parent to offspring. • The genetic material contains information that controls how the new organism will look and function. TWO MAIN TYPES OF REPRODUCTION • Sexual reproduction is the production of a new organism from two parents. • Asexual Reproduction is the production of a new organism from a single parent. SEXUAL AND ASEXUAL REPRODUCTION • What type of reproduction involves only one parent? • Asexual reproduction • Which type of reproduction requires fertilization? • Sexual reproduction THINK ABOUT IT… • What type of reproduction produced the young spider plants? • Asexual reproduction • Why do the lion cubs look similar to their parents? • During sexual reproduction, they received traits from both parents. ASEXUAL REPRODUCTION PRODUCES AN EXACT COPY OF THE PARENT ORGANISM. WHEN COULD THIS BE A DISADVANTAGE? QUESTIONS… • This could be a disadvantage if the parent organism does not have desirable traits. ASEXUAL REPRODUCTION • There are several methods of asexual reproduction shared by a wide variety of organisms. • Organisms that reproduce through asexual reproduction produce genetic copies of the parent organisms. • Methods • • • • Splitting Budding Other forms without fertilization Vegetative Propagation METHODS OF ASEXUAL REPRODUCTION SPLITTING • Most unicellular protists and bacteria reproduce by splitting into two cells. • First the organism copies its own genetic material. • The two new offspring organisms will then each have a copy of the genetic material they need to carry out life processes. • Some bacteria can divide into two new organisms every 10-20 minutes. BUDDING • Cnidarians, sponges, and some fungi reproduce by budding. • The process of budding: • A small part of the parent’s body grows into a tiny and complete version of the parent. Sometimes, the bud breaks off from the parent organism and continues to grow. Other organisms, such as coral, the newly formed bud remains attached to the parent. OTHER FORMS OF ASEXUAL REPRODUCTION • Fish, insects, frogs, and lizards reproduce without fertilization taking place. • The females produce egg cells, but the egg cells are not fertilized. They develop into a new animal without fertilization. • Queen bees- Some of their eggs are fertilized and some are not. The fertilized eggs develop into females, or worker bees. The unfertilized eggs become males, or drone bees. VEGETATIVE PROPAGATION • A form of asexual reproduction in plants that produces new plants from leaves, roots, or stems. • Runners are plant stems that lie on or under the ground and sprout up as new plants. • Strawberry plants, ferns, and most grasses reproduce by growing runners. HOW DO YOU KNOW THAT THE OFFSPRING FROM ASEXUAL REPRODUCTION WILL BE EXACTLY LIKE THE PARENT? • They inherit the genetic material of the parent. They have the same traits as the parent. • http://mrsdlovesscience.com/asexualrepro.html LOOK AT THE IMAGES OF SPLITTING AND BUDDING ON P. 92. • What is the most important difference between the processes? • Splitting occurs as single-celled organisms split into two cells. Budding involves a small part of the parent’s body that grows into a new individual. QUESTIONS… • Describe the steps in bacteria reproduction. • First, the organism produces a copy of its genetic material. Next, the organism splits into two new individuals. WHAT IS THE DIFFERENCE BETWEEN A DRONE AND A WORKER BEE? • A drone is a male bee and develops from an unfertilized egg. A worker bee is female and develops from a fertilized egg. WHAT PART OF THE STRAWBERRY PLANT CAN PRODUCE NEW PLANTS WITHOUT SEEDS? •The stem LET’S READ PGS. 94-95. • What do all seeds need to germinate? • Water • Soil • Warm temperatures WHAT DO YOU THINK IS INSIDE SEEDS? • No matter what size the seed is, they all contain a small embryo plant surrounded by a food supply. • Why do you think seeds have a seed coat? • To protect them WHAT IS THE FUNCTION OF THE FRUIT? • It protects the seed. HOW DOES A BIRD’S EGG PROTECT THE EMBRYO DEVELOPING INSIDE? • The shell keeps the embryo from drying out. The yolk provides food for the developing embryo. SEED COAT • What do you wear to protect you from cold, wind, rain, or snow? • A coat • Just like your coat protects you, the coat on a seed protects the seed from the environment. HOW IS A FISH OR AN AMPHIBIAN EGG PROTECTED? • By a jelly-like layer that surrounds the egg. Fish Eggs Frog Eggs GERMINATION OF A SEED • Describe the sequence of events that lead to the germination of a seed. • A seed is produced. The seed develops and falls from the parent plant. Wind carries the seed to a new location. The seed will germinate if conditions are right for growth. • A volcanic island in the ocean has no plants growing on it. Soon seed plants appear. How might these seeds have reached the island? • Seeds could have blown there with wind, floated there as fruits or seeds in the water, or been carried there by animals. LET’S READ PGS. 96-97. • Yeast are fungi that reproduce through budding. Other fungi can reproduce asexually by producing spores. Some fungi also reproduce sexually. WHAT IS A SPORE? • A reproductive cell that is produced through cell division. When conditions are right, a spore can produce a new organism. WHAT ARE FRUITING BODIES? • Reproductive structures of some fungi that produce spores HOW ARE MUSHROOM SPORES DISPERSED? • Some spores are dispersed by the wind; others are dispersed by insects. YEAST PRODUCTION • Describe the steps in yeast reproduction. • Yeast reproduce through budding. Budding begins when a small growth forms on the parent cell. The nucleus divides into two. One of the two nuclei become part of the bud. The bud finally breaks off and lives as a new organism. STINKHORNS ARE FUNGI THAT SMELL LIKE ROTTING MEAT. HOW COULD THIS CHARACTERISTIC HELP THESE FUNGI DISPERSE THEIR SPORES? • If a stinkhorn fungus smells like rotting meat, it may attract insects. When an insect comes in contact with a stinkhorn fungus, the spores may stick to it. The spores may be dispersed in a new location when the insect flies away. ASEXUAL AND SEXUAL REPRODUCTION DIFFERENCES • Asexual Reproduction: • only one parent • offspring identical to the parent • Sexual Reproduction: • two parents • Offspring have a combination of the parents’ traits WHY IS IT AN ADVANTAGE FOR AN ORGANISM TO BE THE PRODUCT OF SEXUAL REPRODUCTION? • It provides variety in the offspring and in a species. Offspring might be better suited to environmental changes than the parents. HOW CAN YOU TELL THAT THESE PUPPIES ARE NOT THE RESULT OF ASEXUAL REPRODUCTION? • The puppies all look different, which means they have traits from both parents. They are the result of sexual reproduction. DESCRIBE THE SEQUENCE OF EVENTS THAT COULD HAPPEN TO A MOUSE POPULATION IF ORGANISMS THAT EAT MICE MOVED INTO THEIR HABITAT? • Organisms that eat mice appear. The slow mice get eaten. The fast mice survive and reproduce. The mouse population then changes to mostly fast mice. WHAT IS AN ADVANTAGE OF ASEXUAL REPRODUCTION? • Asexual reproduction can occur without a mate.