Chapter 8: Plant and Animal Life Cycles

Lesson 1: Plant Structures

What Are the Functions of Roots, Stems and Leaves?

Roots Roots anchor a plant in the ground, absorb water and minerals from the soil, and sometimes store food. Fibrous Dense, tangled mass Pull a lot of soil when removed from ground Grass, corn and onions Taproot Long, thick main root- with many smaller roots Hard to pull out of the ground Carrots, dandelions and cacti

Root Structure The tip is covered by the root cap. Underneath the cap are cells that divide Root hairs can enter spaces between soil particles- absorbing water and minerals. Anchor plant into soil. Water and nutrients moved by xylem Food made in the leaves and root are moved in the phloem Root Structure

Stems The stem carries substances between the plant’s roots and leaves. The stem also provides support for the plant and holds up the leaves so they are exposed to the sun. Woody Hard and rigid, many layers: outer layer of bark, vascular phloem, cambium which produces xylem and phloem, xylem, heartwood (older and darker is inactive) Herbaceous Often soft Daisies, ivy and asparagus

Annual Rings Used to report a trees yearly growth Xylem rings from the spring are large and have thing walls making a wide, light brown ring Xylem rings that form in the summer grow slowly and have thin dark rings. One pair of light and dark represent a year of growth. The width can tell weather conditions (rain, drought, etc.)

Leaves Leaves capture the sun’s energy and carry out the food-making process of photosynthesis. Leaves have different shapes and sizes

The Structure of a Leaf The top and bottom layers of a leaf protect the inside. Between the layers of cells are veins that contain xylem and phloem. Surface layers have stomata, which are pores that allow gases to enter and leave.

The Leaf and Photosynthesis The cells that contain the most chloroplast are located near the upper surface. Carbon Dioxide enters through the stomata. Water enters through the roots and to the stem by the xylem. Sugar and oxygen are produced from the carbon dioxide and water. The sugar travels through the plant by the phloem.

Controlling Water Loss Transpiration is the process by which water evaporates from a plant’s leaves. They can lose a ton of water in the summer! Plants can control transpiration. Closing the stomata

How Do Seeds Become New Plants? Inside a seed is a partially developed plant. If a seed lands in an area where conditions are favorable, the plant sprouts out of the seed and begins to grow.

Seed Structure The seed has three main parts Embryo Stored food Young plant that develops from the zygote Has beginnings of roots, stems, and leaves Stored food Used by embryo until it can make its own food through photosynthesis Seed coat Acts like plastic wrap, protecting embryo and food from drying out. ** Most seeds are surrounded by a structure called fruit

Seed Dispersal Seeds can move in many different ways: Animals eat fruit and the seeds inside the fruit pass through the animals digestive system and deposited in new areas Some seeds can attach to fur or clothing Water Wind Some plants eject their seeds ** seed dispersed far from parent has a better chance of survival because it isn’t competing for light, water and nutrients.

Germination Process by which the embryo begins to grown again and pushes out of the seed. Begins when the seed absorbs water Uses store food to being to grow Roots grown downward Then stem and leaves grow upward.

What Are the Structures of a Flower?

Flowers come in all sorts of shapes, sizes and colors. Colors and scents attract insects and other animals. These objects help transfer pollen made from male reproductive structures, to female reproductive structures (pollination) Pollinators can be birds, bats, insects (bees and flies)

Sepals and Petals Leaf like structures are called sepals Protect the developing flower and are typically green Flowerlike structures are called petals Most colorful part of the flower Stamens Male reproductive parts Filament is the think stalk structure Anther is where pollen is made at the top of the filament Pistils Female reproductive part Sticky top is called the stigma Slender tube is called the style Attaches to ovary which protects the seed as it develops

Lesson 2: Plant Reproduction Like other living things, plants develop and reproduce through life stages.

What Are the Stages of a Plant’s Life Cycle? Plants have complex life cycle that include two different stages, the sporophyte stage and the gametophyte stage. Sporophyte- plant produces spores (seeds), which grow into new organisms. The spore developes further into a gametophyte stage. This is where the plant produces two cells. Sperm Egg

Angiosperms are classified based on the length of their life cycles. Annuals complete their growth in one growing season. Marigolds, petunias, wheat, cucumbers Biennials complete their life cycle in two years. 1st year- roots, short stems, leaves 2nd- lengthen stems, grow new leaves, produce flowers and seeds. Parsley, celery, foxglove Perennials live for more than two years and mostly flower every year Grasses, trees, tulips

How Do Plants Reproduce? Structures and environment differ in reproduction. Fertilization occurs when a sperm cell unites with an egg cell. This forms a zygote. Most need water in the environment because the sperm cells swim through the water. Other plants have adapted to dry environments.

How Do Plants Reproduce? Asexual reproduction requires only one parent. And produces offspring that are identical to the parent. New plants can grow from the roots, stems or leaves of the parent plant. This DOES NOT involve flowers, pollination or seeds– it can happen faster. This doesn’t offer a variety of genetic information.

How Do Plants Reproduce? Scientists can create identical plants for experiments. They can use grafting to copy plants. They cut the stem and attach it to another related plant species. This allows the plant to produce more than one kind of fruit.

Nonvascular and Seedless Nonvascular Plants Plants release spores to their surroundings and grow into gametophytes. These must use the water to continue to unite the egg and sperm in the next stage. WIND and WATER help carry the spores distances (into moist and muddy areas) which can help with the gametophyte stage. Mosses, liverworts, hornworts, ferns, club mosses, and horsetails.

Gymnosperm Reproduction Cone Production Reproductive structures called cones Male and female cones. Some make both, some make only one, and some make neither. Pollen Production and Ovule Development Male produce pollen grains which make sperm. Female develop in ovules that contain egg cells. This later develops into a seed.

Gymnosperm Reproduction 3. Egg Production Two cells form inside each ovule on the female cone. 4. Pollination Transfer of pollen from male to female Wind helps Pollen collects on sticky substance made by the ovule 5. Fertilization Ovule closes and seals in pollen. Scales close Sperm fertilizes egg and zygote develops

Gymnosperm Reproduction 6. Seed Development Female cones stay on tree while seed mature Can take two years for maturity Male fall off after they shed pollen 7. Seed Dispersal When mature, scales open Wind shakes out seeds and carries them away Only a few will find good places to grow into new plants

Angiosperms Pollination Fertilization Grain of pollen falls onto stigma. Can be done by wind Can drop as an animal leaves. Pollen can be brushed onto the stigma of the next flower as an animal visits Fertilization If pollen falls on the stigma of a similar plant, fertilization can occur The sperm joins with the egg in the ovule at the base of the flower.

Angiosperms Fruit Development The ovary changes into a fruit as the seed develops. Apples, cherries, tomatoes, squash, berries Animals that eat fruits help disperse seeds by depositing them in new areas.

Angiosperm Reproduction

Lesson 3: Animal Reproduction and Fertilization Animals undergo either sexual or asexual reproduction to make more of their own kind or own species. Reproduction is essential to the survival of a species.

ASEXUAL REPRODUCTION Certain kinds of worms can survive being cut in half. They form new worms from their pieces. We call this regeneration. Budding is another example of asexual reproduction. A new animals grows out of the parent and breaks off. This organism receives an identical copy of the parent’s set of genetic material or DNA. Examples: animals, including sponges, jellyfish,, sea anemones, worms and the hydra (p 269).

SEXUAL REPRODUCTION You have developed after a sperm and egg join. They carry DNA that determines physical characteristics such as SIZE and COLOR. The DNA of the child is formed from the parents. The offspring have a combination of characteristics from both parents. Most vertebrates, including mammal and most invertebrates reproduce sexually. Some animals may produce both egg and sperm. They fertilize eggs of another, not their own. Examples: mollusks, fishes, and worms

REPRODUCTIVE CYCLES Several aquatic invertebrates such as _________________________, and _________________, have life cycles that ______________________ between sexual and asexual reproduction. Sponges Produce both sexually and asexually. Asexually through __________________________. Small new sponges grow or ____________, from the sides of an adult sponge. Eventually break free and live life on their own. A sponge can produce both _____________ and ____________ cells. After egg fertilized by sperm a _______________ develops. Larva:_________________________________________________________________________

CNIDARIANS Most alternate between two body forms: Polyp: body form that looks like an upright vase Medusa: body form that looks like an open umbrella Some polyps reproduce through budding, others pull apart. Both forms rapidly increase the number of polyps in a short time. Produce sexually when in medusa stage. Release sperm and egg into the water Fertilized egg turns into a swimming larva Larva attaches to hard surface and develops into a polyp that may continue the cycle. Example of Cnidarian: jellyfish

How Do Internal and External Fertilization Occur? External fertilization occurs outside of the female’s body, and internal fertilization occurs inside the female’s body. External Fertilization Examples: fish, amphibians, aquatic invertebrates Must take place in water to prevent the sperm and egg from drying out. Female releases egg into the water The male releases sperm nearby  

INTERNAL Internal Fertilization Many aquatic animals and ALL land animals Male releases sperm directly into the female’s body where the eggs are located. Most invertebrates and many fishes, reptiles, amphibians, and birds lay eggs outside of the body. For most mammals, fertilized eggs develop inside the female animal They give birth to live young The period between fertilization to birth is called gestation. Shortest: opossum Longest: African elephants

Lesson 4: Development and Growth

Where Do Embryos Develop? The growing offspring, or embryos, may develop outside or inside of the parent’s body. Most animals without backbones lay eggs Worms and insects But birds, fishes and reptiles lay eggs too! The egg contains nutrients! This is called an amniotic egg because it is covered with a leathery shell In some animals the egg is contained within the parent’s body. The nutrients come from the egg’s yolk. The egg hatches either before or after being released from the parent’s body. Fish, amphibians, and reptiles.

DEVELOPMENT OF FROGS

In dogs, horses, humans, and other placental mammals, the embryo develops inside the mother’s body. The material exchanged between the embryo and the mother is called placenta. Blood is transferred to the embryo, which carries oxygen and food. Carbon Dioxide and waste are sent out of the embryo Development takes place until the body systems can function on their own!

How Do Young Animals Develop? Young animals undergo changes in their bodies between birth and maturity- when they are able to reproduce. This is called a metamorphosis Crustaceans start out as tiny larvae Shrimp, lobsters, and crabs They do not have the same body structure as larvae as they do an adult.

Amphibians Complete Metamorphosis Incomplete Metamorphosis Cycles of life where there are different stages. (ladybug) Egg: from parent Larva: hatches from egg, looks usually like a worm (think of caterpillars) Pupa: the insect is enclosed in a protective covering while it changes into the adult form (develops wings, legs, antennae) Adult : major body changes occur from pupa stage Incomplete Metamorphosis Has no distinct larval stage!! (chinch bug) Egg: From parent Nymph: looks like an adult insect without wings, sheds exoskeleton a few times before becoming an adult Adult : final growth stage Amphibians Frogs begin their life cycle as a fertilized egg in the water. The larvae are called tadpoles. They look different than adult frogs

How Do Animals Care for Their Young? Most amphibians and reptiles do not provide prenatal care, while most birds and mammals typically care for their offspring. No Parental Care Eggs are released into water and then are completely ignored Aquatic invertebrates, fishes and amphibians Larvae and tadpoles are left to develop by themselves Are able to care for themselves at the time of birth Parental Care Most birds and all mammals spend weeks to years under the care and protection of a parent. Birds Birds lay their eggs in nests One or both parents keep the eggs warm Some can find food, others must be fed by the parent Mammals After birth, young mammals are fed with milk form their mother The mammals aren’t on their own until they are independent