Living Things Around Us PDF

# Living Things Around Us ## Hot Concept - Have you ever been to a farm? - Are you an animal lover? - If yes, you might have noted that animals have different characteristics. - They have features that keep them alive. - These characteristics suit the environment they live in. - This characteristic...

# Living Things Around Us ## Hot Concept - Have you ever been to a farm? - Are you an animal lover? - If yes, you might have noted that animals have different characteristics. - They have features that keep them alive. - These characteristics suit the environment they live in. - This characteristic is called **adaptation**. - If animals are not adapted to the environment, they are unlikely to survive. - Adaptation can be natural or behavioral. - Whether the animals live on land, in water, or both, their body structures and behaviors are **adapted** to their environment. ## Terrestrial Animals: Animals That Live on Land - Animals that live on land have unique features in their body coverings. - They use these for protection, as a way of getting their food, and for respiration. ### Structural Adaptation #### Body Covering - Animals use their body coverings for protection and temperature regulation. - There are four kinds of body coverings evident in terrestrial animals: - fur or hair - feathers - scales - shells - What do you think would happen if polar bears do not have thick fur? - They will not survive their cold habitat. - This is similar to why you need to wear thick clothes during cold weather. - So, fur is responsible for keeping the bodies of animals such as polar bears warm. - Other animals with fur or hair are lions, monkeys, cats, and rabbits. #### Figure 4.1 Animals with fur - Lion - Cat - Rabbit #### Another body covering of animals is feathers. - The animals covered with feathers are birds. - Similar to fur, feathers keep the bodies of birds warm. - It also enables them to fly. #### Figure 4.2 Animals with feathers - Eagle - Ostrich - Chicken ### Behavioral Adaptation - Animal behavior differs to ensure that they are protected from being eaten by other animals. - Terrestrial animals use camouflage, mimicry, living together, and running speed to escape from their predators or the animals that want to eat them. #### Camouflage - To avoid being eaten, some animals blend their colors with the environment. - This makes them difficult to spot by their predators. - For example, the greenish color of grasshoppers makes them hard to locate by other animals because they blend with the green grasses and other plants. #### Mimicry - Another way to escape from predators is to mimic or copy the features such as shape, sound, taste, color, or smell of stronger or poisonous organisms. - Copying these characteristics makes them look poisonous or stronger as well. - This will prevent other animals from eating or attacking them. #### Living and Traveling Together - Giraffes, tigers, elephants, zebras and lions are examples of animals that live and travel together. - They do so because they need to protect one another whenever other animals try to attack them. #### Running Speed - Running speed is an advantageous trait for animals that chase their prey. - An example of an animal with this trait is the cheetah. - Aside from chasing other animals for their food, they use their fast speed in running to hide from animals that might attack them. ## Aquatic Animals: Animals That Live in Water - Animals that live in water have features adapted to aquatic environments. - They have unique characteristics in their body coverings for protection, as a way of getting food for nutrition, for respiration, and as a way of giving birth. ## Reproductive System of Representative Animals - What does it feel to have a new puppy or kitten? - If you treat pets as part of your family, having a new member of the family feels wonderful. - How about butterflies, mosquitoes, and frogs? - Do you know how these animals reproduce? - In this lesson, you will learn about the modes of reproduction of these representative animals. ## Mode of Reproduction of Insects: Butterflies and Mosquitoes - Butterflies are known for the beautiful patterns on their wings. - These wings are not only for aesthetic purposes, but they also serve as mate recognition. - Male butterflies look for potential female mates by recognizing the size, color, shape, and vein structure of their wings. - Once they find the right mate, they will join together end to end at their abdomens. - Similar to other animals, the male produces sperm and passes it through the female reproductive tract. - Once the sperm fertilizes the egg, a new butterfly will be born. ### Big Idea - Fertilization is the start of having a new organism. - Unlike butterflies, mosquitoes are always linked to diseases such as malaria or dengue. - However, how do they mate? - You must be aware that DOH warns people to not leave any stagnant water as this is a perfect breeding ground for mosquitoes. - Mosquitoes need to get blood meal to nourish their eggs. - Once they do get it, they are able to lay one batch of eggs. ### Do It Right - Clean the environment. - Make sure that there is no stagnant water in your place to eliminate breeding grounds of mosquitoes. - Your safety depends on your cleanliness. ## Mode of Reproduction of Frogs - Have you heard croaking sounds at night? - These are produced by male frogs. - They make these sounds to attract female mates. - Once it finds its mate, the male frog grasps and embraces the female frog in a position called amplexus. - This mating position of frogs aligns the cloaca (opening through which the male releases sperm and through which the female releases eggs) to ensure efficient fertilization. - Fertilization and embryo development occur outside the female frog's body. - This kind of fertilization is called external fertilization. ### Big Idea - Animals that undergo external fertilization release a large number of eggs to ensure a higher rate of survival. ## Modes of Reproduction of Mammals: Cats and Dogs - Loud, frequent, and indiscriminate sounds of cats are often heard during mating. - The breeding process starts with the female "heat cycle." - This occurs when female cats reach puberty. - It usually starts when the cat is approximately six months old. - The heat cycle lasts up to two days but is repeated every two to three weeks. - This cycle is important because it is the time when the cats are ready for mating. - Dogs also have a heat cycle, but there are various stages with specific events. - During the first part of the cycle, the female dog shows a swollen vulva and exhibits bleeding. - The male dog will then be attracted and give more attention to this female dog, but he is not allowed to mount her yet. - This stage lasts for approximately seven days. - In the next stage of the cycle, slowing down of bleeding is evident. - This is also the time when the female dog accepts mates. - It also lasts for approximately seven days. - In the last stage of the cycle, the female is more likely to no longer accept mates. ### Checkpoint - 1. What process is similar to all representative animals? - 2. What is the similarity of the modes of reproduction of dogs and cats? ### Let's Find Out! - **Similarity and Difference between Representative Invertebrates** - **Materials**: Pictures of these animals: crab, earthworm, squid, sea star (starfish), jellyfish or corals, sponge, fluke, and Ascaris worm - **Procedure:** - Form groups with 5 members each. - Prepare the pictures of the eight animals on a table. - With your group mates, choose two animals. - Think of any similarities and differences between the two animals. ### Reflect Upon - What adaptations do frogs have for reproduction, considering that they do not have structures such as the penis? ## Hot Concept - Have you ever asked your mother how you and your siblings were born? - Do all animals give birth to young similar to humans? - Animals reproduce in various ways. - The two types of reproduction are sexual and asexual. - The main differences between the two types of reproduction are the number of parents needed and the similarity of the offspring to the parent. ### Sexual Reproduction - Sexual reproduction involves mating of two parents of different sexes to produce an offspring. - As a result, the young has mixed traits from its mother and its father. - On the other hand, asexual reproduction involves only one parent. - So, the offspring is the exact copy of its parent. - In sexual reproduction, some animals give birth to new animals that are either hatched from eggs or born alive. ## Animals That Lay Eggs - The representative animals in the previous discussion have reproductive organs that produce eggs for females and sperm for males. - Offspring will be produced when the egg and sperm meet. - This process of the union of egg and sperm is known as fertilization. - There are two types of fertilization: external and internal. - External fertilization is when the egg is fertilized outside the mother's body. - If fertilization occurs within the mother's body, it is internal fertilization. - It has three types: oviparous, viviparous, and ovoviviparous. - The frog is an example of an animal that lays eggs but the eggs are fertilized externally. - During amplexus, the female frog releases eggs. - The male frog will then release his sperm over the eggs. - The union of eggs and sperm will occur in the water and not within the female's body. - The egg released by frog is enclosed in a jellylike sac. - This protects the egg from the strong movement of the water. - However, it is easily seen by predators so frogs release a large number of eggs. - This increases the chance for more eggs to be fertilized and then develop. - Other animals that lay eggs but are fertilized externally are bony fish, shrimp, crab, oyster, squid, sea urchin, sea cucumber, and other amphibians. ### Big Idea - Sexual reproduction involves passing on of genes from both parents to their offspring. - This is the reason that this type of reproduction increases genetic diversity or the uniqueness in organisms. ## Animals That Are Born Alive - Not all animals lay eggs. - Others give birth to live animals. - There are two kinds of animals that produce live young: viviparous and ovoviviparous animals. - Viviparous comes from the Latin words vivi, which means "alive,” and parum, which means "bearing." - Ovoviviparous is a combination of the Latin words ovum, which means "egg," vivi, which means "alive," and parum. - Cats and dogs are viviparous animals. - They do not lay eggs. - These animals have a placenta, which supplies nourishment to the developing embryo. - Other viviparous animals are some fishes and many mammals except monotremes. - An example of an ovoviviparous animal is the shark. - It also gives birth to live young. - However, the young do not receive nourishment from the placenta. - It gets nutrients from the yolk of the egg. - This is the reason that it is considered ovoviviparous. - Nourishment comes from the eggs, but they are hatched inside the mother's body; thus, the animal gives birth to live offspring. - Other ovoviviparous animals are some bony and cartilaginous fishes and some reptiles. ### Checkpoint - 1. Differentiate external and internal fertilization. - 2. What are the adaptations shown by animals that lay eggs and animals that are born alive? ### Asexual Reproduction of Animals - Reproduction can still be possible even if there is only one parent. - In animals, this is only possible in some invertebrates. - All vertebrates reproduce sexually. - There are various types of asexual reproduction in animals: binary fission, budding, and fragmentation. - Table 4.2 shows a representative animal under each invertebrate group and the type of asexual reproduction it exhibits. #### Table 4.2 Asexual Reproduction Exhibited by Some Representative Animals | Invertebrate Group | Representative Animal(s) | Type of Asexual Reproduction| |:--:|:--:|:--:| | Porifera | Sponge | Fragmentation | | Cnidaria | (a) Sea anemone (b) Hydra | (a) Binary fission (b) Budding | | Echinodermata | Sea star | Fragmentation | | Platyhelminthes | Planarian | Fragmentation | - Fragmentation is a type of asexual reproduction wherein "fragments" of the animal's body are able to grow into new separate organisms. - Figure 4.15 shows fragmentation in a planarian. - The body of the planarian is cut into four fragments. - These four fragments will each regrow into new planarians. - Examples of other animals exhibiting this type of reproduction are sponges, corals, and sea stars. #### Figure 4.15 Fragmentation in a planarian #### Binary Fission - Binary fission comes from the word bi, which means "two," and fiss, which means "separate" or "cut." - It is a type of asexual reproduction wherein an organism splits, forming two new organisms. - An example of an animal showing this type of reproduction is the sea anemone. #### Figure 4.16 A sea anemone undergoing binary fission #### Budding - Budding is a type of asexual reproduction wherein a bud or outgrowth forms in the body of the parent organism. - This bud will grow and will then detach from the parent and become a new organism. - This type of reproduction is seen in hydras and other cnidarians. #### Figure 4.17 Hydra showing the process of budding ### Big Idea - Organisms reproducing asexually have higher chances of getting extinct. - This is because if one organism is not adapted to the changing environment, all the other organisms of the same kind will die as well. ### Do It Right - Conserving coral reefs is important. - Fragmentation would work to have new corals and save coral reefs. ### Big Idea - Asexual reproduction is evident only in some invertebrates. - It can be through fragmentation, binary fission, or budding. ## Hot Concept - The Reproductive System of Flowering Plants - A flower symbolizes beauty. - It is not only for aesthetic purposes, but also important in plant reproduction. - Did you know that the flower is the reproductive organ of some plants? - The pistil is the collective term for the female reproductive organs of a flower. - It includes the ovary, ovules, style, and stigma. - The ovary contains the ovules. - The ovules are the female reproductive cells or the egg cells. - The fruits that you eat are actually ripened ovaries. - The seeds are the developed ovules. - The style is a stalk that joins the stigma to the ovary. - The topmost portion of the style is the stigma. - The sticky stigma collects the pollen from various pollinators such as bees, butterflies, birds, bats, rodents, or humans. - Sometimes, pollen is also dispersed by the wind. #### Figure 5.1 The female reproductive parts of a flower - The stamen is the male reproductive organ of a flower. - It includes the anther and the filament. - The anther produces and stores the pollen, which contains the sperm needed in reproduction. - The filament is a long stalk that supports the anther. - It is long to ensure that pollinators will brush against the anther and collect the pollen. #### Figure 5.2 The male reproductive parts of a flower ### Do It Right - Be mindful of your surroundings. - Pollen can be inhaled by humans and cause irritation. - Pollen can also trigger one's allergies. - The other parts of the flower are petals, sepals, and receptacle. - Petals are the pretty part of the flower that give its shape, odor, and form. - Petals come in a wide variety of colors. - Their main role is to attract pollinators, particularly insects such as bees. - Sepals are small leaflike structures at the base of the petals. - They protect the blossoming flower and prevent it from drying out. - The receptacle holds the major organs of the flower. ## The Reproductive System of Nonflowering Plants - Not all plants have flowers. - Some plants have cones or spores as their reproductive organs instead. - These plants are called nonflowering plants. - Similar to flowers, cones have female and male reproductive parts. - The female cone is called an ovulate cone because it encloses the ovules containing the egg cells. - The male cone is called a pollen cone because it has pollen, which contains the sperm cells. - The female cones are bigger and harder than the male cones. - They are found at the upper branches of the tree to ensure the likelihood of the pollen meeting the ovules, a process known as pollination. - The parts of the cone are the cone scale and winged seed. - In females, the cone scale encloses and protects the seed. - The seed has wings to aid in dispersal. - In males, the cone scale has two pollen sacs, which open and release the pollen. ### Big Idea - Flowers are the reproductive organs of flowering plants. - They have female and male parts. #### Figure 5.3 Ovulate cone and pollen cone ### Big Idea - Cones are the reproductive organs of some nonflowering plants. ## The Reproductive System of Spore-bearing Plants - Reproductive parts in plants are not limited to flowers and cones. - Some plants such as ferns, mosses, and other spore-bearing plants have reproductive parts that enable them to switch or alternate from a sexual phase to an asexual phase in their life cycle. - The sporophyte is responsible for the asexual phase, whereas the gametophyte is for the sexual phase. - The sporophyte produces spores, and the gametophyte produces gametes (egg and sperm). ## Sporophyte - The sporophyte of ferns has a sorus underneath. - The sorus (plural: sort) is a brownish or yellowish pepper-like cluster of spore-producing structures. - When they land on the soil, these spores will become new ferns. - In a moss, the sporophyte has a seta and a capsule. - The seta is a stalk that transports nutrients from the base of the sporophyte to the capsule. - The capsule is the site of spore production. #### Figure 5.4 (a) Fern sporophyte; (b) moss sporophyte ## Gametophyte - The structures that produce and contain the egg and sperm are the archegonium and the antheridium, respectively. - In ferns, the archegonium and antheridium are both found in a single gametophyte. - In mosses, they are located in separate gametophytes. #### Figure 5.5 Male and female gametophyte in (a) fern and in (b) moss ### Checkpoint - 1. What are the reproductive organs of flowers that produce eggs and sperm? - 2. Differentiate pollen cone and ovulate cone. - 3. What is the difference between gametophyte and sporophyte? ### Reflect Upon - Why do flowers come in different colors? - Relate your answers to how these plants reproduce. ###Big Idea - Spore-bearing plants undergo both sexual and asexual phases in their life cycle. - Gametophytes and sporophytes are involved in their reproduction. ## Kinds of Plants - You have learned that plants have male and female reproductive organs, just like animals, including humans. - They may be different in structures, but the types of reproductive cells they produce are similar. - Male organs are always associated with producing pollen, which contains sperm, whereas female organs have one or more ovaries that contain ovules, where eggs develop. - Some plants contain both male and female reproductive organs. - They are called monoecious plants. - Others contain either the male or the female organ only. - They are called dioecious plants. ## Monoecious Plants - Monoecious comes from the Greek words monos, which means "single,” and oikos, which means "house." - This means that a single monoecious plant houses both male and female parts. - In flowering plants, the flower can be bisexual or unisexual. - In bisexual flowers, the male and female parts are found in a single flower. - Roses, lilies, tulips, and gumamela are examples of bisexual flowers. - In unisexual flowers, a single flower can have either the male or the female part only. - However, this male or female flower is found in the same individual plant. - Squash, corn, and birch are examples of plants with unisexual flowers. - Similar to unisexual flowers, most conifers or cone-bearing plants have either the male or female parts only. - Both male and female cones are found in the same plant. - In ferns, the reproductive structures of the male and female are both found in a single gametophyte. ### Big Idea - The main difference between monoecious and dioecious plants is the number of reproductive organs present in a plant. - Monoecious plants have the male and female reproductive structures in a single plant, whereas dioecious plants have female and male structures found in different individual plants. ## Dioecious Plants - Dioecious comes from the Greek words di, which means "two,” and oikos, which means "house." - This means that the male or female reproductive organs are in two different plants. - Ginkgo, kiwi, cannabis, and willow are examples of dioecious plants. - In mosses, the male and female gametophytes are found in different individual mosses. ### Checkpoint - 1. What is the difference between monoecious and dioecious plants? - 2. Give two examples of monoecious plants and two examples of dioecious plants. ## Hot Concept - Sexual Reproduction in Flowering Plants - What role do flowers play in reproduction? - The flower's color, shape, smell, and size are characteristics that attract specific pollinators. - Pollinators such as bees, butterflies, birds, bats, rodents, or humans transfer the pollen from one flower to another. - This pollen transfer, also known as pollination, makes fertilization in plants possible. ### Pollination - Pollination can be classified into two: self-pollination and cross-pollination. - Self-pollination is when the pollen is transferred to the stigma of the same flower. - Self-pollination can also occur by transferring the pollen to the stigma of another flower of the same plant. - On the other hand, cross-pollination is when the pollen is carried by wind, water, or pollinators from one flower to another. - In this type of pollination, the flowers involved are not in the same individual plant. #### Figure 5.6 (A and B) Self-pollination and (C) cross-pollination ### Fertilization - During pollination, the pollen lands on the stigma. - When this happens, the pollen grain grows a pollen tube. - It passes through the style until it reaches the ovules in the ovary. - This event makes fertilization possible. - Recall in the previous chapter that fertilization is the process wherein the egg and the sperm unite, forming an embryo. #### Figure 5.7 Fertilization in flowering plants ### Post-fertilization - Once fertilization is done, the ovule becomes the seed and the ovary matures into a fruit. - This ripened ovary is the one that you eat. - Its seeds are the developed ovules. - The seed will then grow into a seedling and become a plant later on. - Flowers will be produced by the mature plant. - Then the cycle repeats. #### Figure 5.8 The life cycle of flowering plants ### Sexual Reproduction in Nonflowering Plants - Have you ever wondered why cones are simpler in structure than flowers? - This is because of the agents in pollination. - The agents of pollination in flowering plants are the pollinators, whereas in nonflowering plants, the wind is the one that mostly aids in pollination. #### Pollination - Flowers have features that can attract pollinators. - This is to ensure that pollination, which is important in reproduction, will take place. - The cone is simpler (or has fewer parts) because it does not need to attract any pollinators. - Pollen transfer is possible mostly because of the wind. - This is the reason that seeds have wings to help in dispersal. - The wind is also the reason that female cones are usually located at the upper branches of the tree, while the male cones are in the lower branches. - This strategy ensures that the chances of pollen meeting the ovules are high. - So, we can see that for nonflowering plants such as those that bear cones, the wind is the primary agent of pollination. #### Fertilization - Similar to flowering plants, a pollen tube will also grow once the pollen grain lands on the female cone. - Once the pollen tube eventually reaches the ovule, fertilization takes place. #### Figure 5.9 The life cycle of nonflowering plants ### Big Idea - Pollinators are a vital part of reproduction in flowering plants. - Without them, fertilization will not be possible. ### Big Idea - Pollinators such as insects and other animals are not necessary in the reproduction of nonflowering plants. - The wind will mostly be responsible for the pollen transfer. ## Table 5.1 Characteristics of Each Type of Natural Vegetative Reproduction in Stems | Characteristic | Location of the stem | Orientation of the stem | Shape and Appearance | Examples | |:--:|:--:|:--:|:--:|:--:| | Bulb | Underground | Vertical | It is round shaped with a pointed end from which the leaves emerge. It consists of fleshy leaves. Its appearance is layered on the inside. | Onion, lily, and tulip | | Corm | Underground | Vertical | It is oval-shaped and consists of papery leaves. Its appearance is solid on the inside instead of layered appearance. | Crocus and gladiolus | | Rhizome | Underground | Horizontal | Adventitious roots are evident throughout the length of the rhizome. | Ginger | | Tuber | Underground | Vertical | The eyes of potatoes indicate where the nodes are found. | Potato | | Runner | Along the soil | Horizontal | The tip portion develops buds that grow into new clone plants. | Strawberry | ## Artificial Vegetative Reproduction - Horticulturists are garden cultivation and management experts who propagate plants in an artificial manner. - They employ this process to enhance crop quality and reduce difficulty in plant propagation. - Cutting, layering, and grafting are the types of artificial vegetative reproduction. ### Cutting - The stems, roots, and leaves of some plants can be removed and planted in the soil. - These cut portions will grow into new individual plants. #### Table 5.2 Types of Cutting | Type of Cutting | Examples of Plants | |:--:|:--:| | Stem cutting | Rose, bougainvillea, and potato | | Root cutting | Tamarind and lemon | | Leaf cutting | Begonia and peperomia | ## Structural Adaptation - Aquatic animals use their body coverings for protection. - There are three kinds of body coverings evident in aquatic animals: scales, shells, and spiny, tough body coverings. #### Figure 4.6 Body coverings of aquatic animals- (a) scales of a fish, (b) shell of an oyster, (c) spiny cover of a sea urchin - Scales are an overlapping body cover of fishes. - These serve as protection and aid them to move smoothly in water. - Shells, on the other hand, are evident in oysters, mussels, and clams. - Waves can push them repeatedly; so their shells serve as protection to keep them safe. - Lastly, some aquatic animals such as sea urchins and sea stars (starfishes) use their spiny and tough body covering to prevent other animals from eating them. ### Way of Getting Food - Some aquatic animals are filter-feeders. - These animals filter the water to trap food such as small animals and plankton (tiny organisms living in the seas and oceans). - Oysters use their gills, and baleen whales use their comblike mouths called baleen to filter the water and obtain food. #### Figure 4.7 Adaptation of aquatic animals to obtain food-(a) baleen of a whale and (b) streamlined body shape of a shark - Other aquatic animals such as barracuda, sharks, and other fishes have streamlined body shapes. - The mouth and tail parts of animals with this body shape are narrower than the middle section of their bodies. - This body shape offers faster speed to aquatic animals. - So, they are able to chase smaller fish or other animals for food. ### Respiration - Most aquatic animals have gills as their main organ for respiration. - Gills obtain oxygen from the water that passes through them. - However, there are other aquatic animals that do not have gills but use lungs instead. - These animals include dolphins and whales. - A special structure called the blowhole is similar to the nose of a terrestrial animal. - The blowhole is the part located at the top of the head of dolphins and whales. - Blowholes open when they reach the surface of water to get oxygen. - They close when the animals are underwater to prevent water from going into their lungs. #### Figure 4.8 Adaptation of aquatic animals for respiration-(a) gills of a fish and (b) blowhole of a dolphin ### Behavioral Adaptation - Aquatic animals have different behaviors in protecting themselves. - Some animals such as the squid, octopus, and cuttlefish squirt ink to push their enemies away. - Other animals such as the jellyfish have tentacles that secrete poison. - This allows them to defend themselves from animals that try to attack them. - They also use this poison to capture their prey. ### Big Idea - Animals adapt to the environment where they live in. - In the previous discussion, animals have been classified based on habitat. - In this part of the lesson, a more specific classification will be discussed. - We will classify animals based on whether they have backbones or not. - These animals are called vertebrates and invertebrates, respectively. - More than 90% of all animals are invertebrates. - These animals do not have a backbone. #### Figure 4.9 Examples of vertebrates are jellyfish, sea star, and octopus. - Animals that have a backbone are called vertebrates. - Some of these are fishes, amphibians, reptiles, birds, and mammals. #### Figure 4.10 Examples of vertebrates are stingray and peacock. ## Post-fertilization - Seeds enclosed by the cone scales need to touch the ground to germinate. - This is possible because of the wind or animals. - The wings of the seeds help them in proper seed dispersal. - In other instances, cones fall and then release the seeds contained in them. - Seeds will then grow and develop into a mature plant. - Then the cycle repeats. ## Reproduction in Spore-beaning Plants - As discussed in the previous lesson, the alternation of sexual and asexual phase is evident in spore-bearing plants such as ferns and mosses. ## Reproduction in Moss - In the asexual phase of mosses, the capsule in the mature sporophyte produces and releases spores. - When spores touch the soil, they will start to grow into new mature plants (gametophytes). - In the sexual phase, the gametophyte is dominant. - The sperm from the male gametophyte will fertilize the egg in the female gametophyte. - The surrounding should be damp so that sperm can swim toward the egg. - This is the reason that mosses are found in damp environments. ### Do It Right - Be wary of your health condition. - If you know that you have allergies or asthma, refrain from planting male trees in your surrounding because the pollen released by male trees might trigger your allergies. ## Reproduction in Ferns - In the asexual phase of ferns, the sorus of the sporophyte releases spores. - Similar to mosses, when these spores touch the ground, it will grow into a new fern plant (gametophyte). - In the sexual phase, the heart-shaped gametophyte starts the reproduction process by producing eggs and sperm. - Once these sperm and egg unite, the fertilized egg grows into a mature fern plant (sporophyte). - The mature sporophyte can produce and release spores and start the cycle again. #### Figure 5.10 The life cycle of ferns ### Checkpoint - 1. What do spores and seeds have in common? - 2. What is the role of pollination in the reproduction of plants? ## Asexual Reproduction in Plants - Not all plants have flowers or cones for reproduction. - Some plants cannot produce seeds or spores. - If they do not need sperm and egg to reproduce, how do these plants make new ones? - Asexual reproduction is a type of reproduction that does not need egg and sperm. - So, only one parent is needed for a new organism to arise. - This makes the offspring a clone or an exact copy of the parent organism. - In plants, this kind of reproduction is called vegetative reproduction. - Plant parts such as roots, stems, and leaves produce buds, which will grow into a new plant. - This type of reproduction occurs naturally or artificially. ### Natural Vegetative Reproduction - Roots, stems, and leaves grow buds naturally. - These buds become the new plants later on. - In natural vegetative reproduction, no human intervention is needed. #### Roots - When adventitious roots of the plants are planted in the soil, they will form new plants. - This type of reproduction is evident in sweet potatoes and dahlias. #### Stems - Natural vegetative reproduction in stems is considered one of the most efficient. - The different types are bulbs, corms, rhizomes, tubers, and runners. - The characteristics of each type are shown in table 5.1. ## What do snakes and crocodiles have in common? - Their bodies are covered with scales. - Look at your fingernails. - Its composition is the same as scales. - The purpose of scales is to serve as protection from the rough or rocky surfaces where these animals move. #### Figure 4.3 Animals with scales ## The shell is another kind of protective covering of some terrestrial animals. - Examples of animals with shells are turtles and snails. - When there are enemies, they hide their heads and feet in their shells to protect themselves. ## Way of Getting Food - Getting food is a survival skill. - Terrestrial animals have various adaptations to suit their diet. - Some animals such as the cow, horse, carabao, goat, and sheep have flat teeth. - This kind of teeth is suitable for them because they eat grasses, leaves, or other plant parts. - There are also animals with long, pointed teeth such as the tiger, lion, cheetah, and fox. - Their long, pointed teeth let them tear the meat of their prey. - Beaks and talons are important for birds. - Their talons help them catch smaller animals. - On the other hand, the sharp beak is used to tear apart the small animals that they caught. - Have you noticed that the arms and legs of monkeys are long? - These allow them to swing from one branch to another to get fruits and insects, which are their food. - Another unique feature of monkeys is their strong tails. - Some monkeys use their tails to hang on to the branches of trees. #### Figure 4.4 Adaptation of land animals to obtain food-(a) flat teeth of a horse, (b) sharp teeth of a tiger, (c) beak and talons of a bird, and (d) long arms and legs of a monkey ## Respiration - Most land animals breathe using their lungs. - However, some animals such as insects do not have lungs. - These animals have tracheae (singular: trachea), the tiny tubes in their abdomen. - These enable them to get oxygen. - There are also terrestrial animals that live in the soil such as earthworms. - They absorb oxygen through their moist skin. - This is the reason that earthworms must not get dry because they cannot breathe if their bodies are not moist. ### Big Idea - Spore-bearing plants grow from either spores or gametes. - This is the reason that their reproduction involves an alternation of generations. ### Reflect upon - Is it better for plants to undergo sexual reproduction than asexual reproduction? - Why do you say so? ### Big Idea - Animals undergoing sexual reproduction can either lay their eggs or give birth to live young. ### Reflect Upon - What would happen if animals stop undergoing sexual reproduction?