Biology Notes PDF

1.1 Photosynthesis 26 January, 2025 12:26 AM Photosynthesis is the way that plants makes food. They use carbon dioxide and water to make glucose and oxygen. Carbon dioxide + water >> Glucose + oxygen Glucose is a store of chemical energy - Glucose is...

1.1 Photosynthesis 26 January, 2025 12:26 AM Photosynthesis is the way that plants makes food. They use carbon dioxide and water to make glucose and oxygen. Carbon dioxide + water >> Glucose + oxygen Glucose is a store of chemical energy - Glucose is a sugar. (Belongs to a group called carbohydrates) Plants usually make much more glucose than they need to use immediately to store some of it and use later. They store it as starch because glucose is soluble in water which makes it difficult to store inside a cell. A starch molecule is made of thousands of glucose molecules linked together in a long chain. Starch molecules are too big to dissolve in water. They stay as insoluble grains inside the chloroplast. Before testing a leaf for starch, You need to boil it to break down the cell membranes - Iodine + Starch = Blue-black/violet - Iodine = Orange/reddish brown Photosynthesis: How Plants Make Food Plants use carbon dioxide and water to make glucose and oxygen. Word Equation: Glucose: A Source of Energy Unit 1 Page 1  Glucose: A Source of Energy Glucose is a sugar (belongs to carbohydrates). It stores chemical energy for the plant. Why store glucose as starch? Plants make extra glucose and store it for later. Glucose dissolves in water, making it hard to store inside cells. Plants convert glucose into starch because: ✅ Starch is insoluble (doesn’t dissolve in water). ✅ It can be stored safely inside the chloroplast. Structure of Starch: Made of thousands of glucose molecules linked in a long chain. Too big to dissolve in water, so it stays as insoluble grains in the plant. Testing a Leaf for Starch Step 1: Boil the leaf to break down the cell membranes. Iodine Test for Starch: Starch + Iodine Blue-black/violet No starch Iodine stays orange/reddish-brown Unit 1 Page 2 1.2 Mineral salts for plants Fertilizers provide mineral salts, which make the plants grow larger and healthier - although fertilizers are expensive, the cost to farmers is outweighed by the extra money they can get for their crops. Nitrate is needed so that the plant can make proteins. -A plant that has not got enough nitrate can't make enough proteins, so it cannot make enough new cells to grow well. Nitrate is also needed to make chlorophyll, and if a plant does not have enough nitrate it will become yellow instead of green. Plants also need magnesium to make chlorophyll. Unit 1 Page 3 1.3 Plants and water 26 January, 2025 2:36 AM Plants need water for 4 things, support, cooling, transport and photosynthesis. 1. Water for support Water helps them to stand upright. When a plant cell doesn’t contain enough water, it becomes soft and floppy. When all the cells in a plant are like this, the plant collapses. 2. Water for Transport Plants contain long tubes called xylems, which transport water from the roots up to the leaves. - There are mineral salts dissolved in the water, and this is how they are transported around the plant. Most of the water taken up by the roots eventually diffuses out of the plant's leaves as water vapour. 3. Water for cooling When water evaporates, it absorbs heat energy. This cools down the surroundings. The water evaporating inside a plant lead helps to keep the plant cool. 4. Water for photosynthesis Water is one of the reactants in photosynthesis. Unit 1 Page 4 1.4 Flowers 26 January, 2025 2:37 AM The parts of a flower 1. Petals = The colorful part of the flower that attract insects or birds. 2. Sepal = Protects the flower before it blooms (found at the base of the flower) 3. Stamen = The male reproductive part of the flower that contains, - Anther : Produces pollen. - Filament : A stalk that supports the anther. 4. Stigma = The sticky top part that collects pollen 5. Style = A tube like structure connecting the stigma to the ovary 6. Ovary = Contains ovules which develop into seeds when fertilized - Nectar : The sweet liquid produced to let insects and birds feed on. Unit 1 Page 5 1.5 Pollination 26 January, 2025 2:38 AM To help the male gametes get close to the female gametes, pollen grains must be carries from the anthers to the stigma. The transfer of pollen from an anther to a stigma is called pollination. The male gametes of a flower are inside the pollen grains. The female gametes of a flower are inside the ovules. The male gametes cannot move by themselves, so flowers make use of insects, birds or the wind to move their pollen grains. Some of the pollen grains will then be rubbed off onto the stigma. Unit 1 Page 6 1.6 Fertilisation 26 January, 2025 2:39 AM In sexual reproduction, the nucleus of a male gamete and the nucleus of a female gamete is joined together, this is called fertilization. - When the nuclei of the two gametes have joined together, they form a new cell called zygote. When a pollen grain has landed on a stigma, it grows a tube down to an ovule. The male gamete goes down the tube and fuses with the female nucleus inside an ovule producing a zygote. The zygote divides over and over and produces an embryo plant The ovule becomes a seed, with the embryo plant inside it Seed formation The testa is the tough outer coat of the seed. The micropyle is a tiny hole where the pollen tube grows into the ovule. The two creamy-coloured structures are called cotyledons. They contain food stores for the embryo to use when it starts to grow. Unit 1 Page 7 1.7 Fruits 26 January, 2025 2:39 AM Ovaries develop into fruits after fertilization. Fruits contain seeds Fruits have adaptations to help the seeds inside them disperse to new places. Seed dispersal helps to avoid competition with the parent plant. Unit 1 Page 8 For flashcards, etc 26 January, 2025 2:17 AM Question Answer What is photosynthesis? - The process by which plants make food.- Uses carbon dioxide and water to produce glucose and oxygen. What is the photosynthesis equation? Carbon dioxide + Water → Glucose + Oxygen What is glucose? - A sugar that stores chemical energy.- Belongs to a group called carbohydrates. Why do plants store glucose as starch? - Glucose is soluble in water, making it difficult to store in cells.- Starch is insoluble and stored as grains in the chloroplast. What is starch made of? - Thousands of glucose molecules linked in a long chain. Why is starch insoluble in water? - Starch molecules are too big to dissolve. How is starch tested in a leaf? - Boil the leaf to break down cell membranes.- Add iodine: - Starch + Iodine = Blue-black/violet. - Iodine alone = Orange/reddish brown. Why are fertilizers used? - Provide mineral salts for plant growth.- Increase plant size and health. Why do farmers use fertilizers despite the - Extra crop yield outweighs the expense. cost? What is nitrate used for in plants? - To make proteins for new cells.- To produce chlorophyll. What happens if a plant lacks nitrate? - Can’t make enough proteins → Stunted growth.- Can’t make enough chlorophyll → Leaves turn yellow. What other mineral is needed to make - Magnesium. chlorophyll? Why do plants need water? - For support.- For cooling.- For transport.- For photosynthesis. How does water provide support to plants? - Keeps plant cells firm.- Without enough water, cells become soft, causing the plant to collapse. How is water used for transport in plants? - Xylem tubes transport water and mineral salts from roots to leaves.- Most water eventually diffuses out as water vapor. How does water cool a plant? - Water evaporates, absorbing heat energy, cooling the plant. What role does water play in - It is a reactant. photosynthesis? What is the role of petals? - Attract insects or birds with their colors. What do sepals do? - Protect the flower before it blooms. What is the stamen, and what does it - Male reproductive part of the flower. - Anther: Produces pollen. - Filament: Supports the anther. contain? What is the stigma? - Sticky top part that collects pollen. What is the style? - Tube connecting the stigma to the ovary. What does the ovary contain? - Ovules, which develop into seeds when fertilized. What is nectar? - Sweet liquid produced to feed insects and birds. What is pollination? - Transfer of pollen from an anther to a stigma. Where are male and female gametes found - Male gametes: Inside pollen grains.- Female gametes: Inside ovules. in a flower? Questions Page 9  - Male gametes: Inside pollen grains.- Female gametes: Inside ovules. in a flower? How is pollen transferred to the stigma? - By insects, birds, or the wind. What is fertilization? - Joining of the male gamete nucleus with the female gamete nucleus to form a zygote. What happens after pollination? - A pollen tube grows from the stigma to an ovule.- Male gamete travels down the tube and fuses with the female nucleus to form a zygote. What does the zygote develop into? - Divides to form an embryo plant.- Ovule becomes a seed. What is the testa? - Tough outer coat of the seed. What is the micropyle? - Tiny hole where the pollen tube grows into the ovule. What are cotyledons? - Contain food stores for the growing embryo. What do ovaries develop into after - Fruits. fertilization? What is the purpose of fruits? - Contain seeds.- Help seeds disperse to new places. Why is seed dispersal important? - Reduces competition with the parent plant. Questions Page 10 2.1 Plant adaptations 26 January, 2025 2:40 AM A habitat is a place where an organism lives. Plants are adapted to live in their habitats. Plant adaptations often help them get light for photosynthesis. Annual plants grow, produce seeds and die in less than one year. Unit 2 Page 11 2.2 Animal adaptations 26 January, 2025 3:54 AM A desert is a place that gets very little rainfall each year. Animals may have structural and behavioral adaptations that help them to survive in their habitats. Oryx feed mostly at night, when it is cooler, so they do not lose too much water from their bodies by evaporation. During the day, they usually rest in the shade. They make a small depression(dent) in the sand to lie in, so that their body heat is conducted into the cooler ground. Earthworms belong to the group of invertebrates called annelids. They spend most of their time underground, in burrows that they make by eating soil. ○ Earthworms have long, slim, smooth bodies that slide easily through their burrows. They have tiny bristles on their undersides, called chaetae, which can grip the sides of the burrow, this is useful if a predator tries to pull them out. Producers Meaning: Producers are organisms that make their own food using sunlight (photosynthesis) or chemical energy (chemosynthesis). They form the base of the food chain. Examples: Plants: Grass, trees, algae. Other Producers: Phytoplankton, cyanobacteria. Predators Meaning: Predators are animals that hunt, kill, and eat other animals (prey) for survival. Examples: Land Predators: Lion, wolf, hawk. Aquatic Predators: Shark, crocodile. Prey Meaning: Prey are animals that are hunted and eaten by predators. They often have adaptations like camouflage or speed to escape predators. Examples: Land Prey: Rabbit, zebra, antelope. Aquatic Prey: Small fish, shrimp. Scavengers Meaning: Scavengers are animals that feed on dead animals or decaying organic matter. They play an important role in cleaning the environment. Examples: Vultures, hyenas, crabs. Consumers Unit 2 Page 12 Consumers Meaning: Consumers are organisms that cannot make their own food and rely on eating other organisms. They are classified as: 1. Primary Consumers (eat producers): Herbivores like cows and deer. 2. Secondary Consumers (eat primary consumers): Small carnivores like snakes. 3. Tertiary Consumers (eat secondary consumers): Top predators like eagles. Unit 2 Page 13 2.3 Ecology 26 January, 2025 4:11 AM Ecologists are scientists who study organisms in their environment. - This study is called ecology. Ecologists often use sampling techniques. Samplings involves finding results for a small, representative part of the area you are studying. Unit 2 Page 14 2.4 Food webs and energy flow 26 January, 2025 4:27 AM A food web shows how energy is transferred between organisms. - A food web is made up of many interconnecting food chains. Herbivores Meaning: Herbivores are animals that eat only plants or plant-based materials. They have specialized teeth and digestive systems to process plant matter. Examples: Land Herbivores: Cow, deer, elephant, giraffe. Aquatic Herbivores: Manatee, parrotfish. Carnivores Meaning: Carnivores are animals that eat only meat. They often have sharp teeth and claws for hunting and tearing flesh. Examples: Land Carnivores: Lion, tiger, wolf, fox. Aquatic Carnivores: Shark, orca (killer whale). Omnivores Meaning: Omnivores are animals that eat both plants and animals, giving them a versatile diet. Examples: Land Omnivores: Bear, pig, human. Aquatic Omnivores: Sea turtle, some fish species. Detritivores Meaning: Detritivores are organisms that feed on dead organic matter, such as decaying plants and animals. Examples: Earthworms, vultures, woodlice. Decomposers Meaning: Decomposers are organisms that break down dead materials and recycle nutrients back into the environment. Examples: Bacteria, fungi (like mushrooms) Unit 2 Page 15 2.5 Decomposers 26 January, 2025 4:31 AM Decomposers are organisms that get their energy from dead organisms or their waste products. Decomposers help to recycle substances from dead organisms and waste, so that other living organisms can use them. - They break down dead materials and recycle nutrients back into the environment. The fungus made of many tiny thread-like structures, is called hyphae. - The hyphae produce enzymes that digest the starch and proteins in the bread around them. The small molecules that are produced can then diffuses into the hyphae. - The fungus can use them for energy, or for making new cells for growth. Unit 2 Page 16 For flashcards, etc 26 January, 2025 2:41 AM Question Answer What is a habitat? - A place where an organism lives. How are plants adapted to their habitats? - Plants are adapted to live in their habitats. Why are plant adaptations important? - Help plants get light for photosynthesis. What is the life cycle of annual plants? - Grow, produce seeds, and die in less than one year. What is a desert? - A place that gets very little rainfall each year. What are animal adaptations? - Animals may have structural and behavioral adaptations to survive in their habitats. How do oryx survive in the desert? - Feed mostly at night when it’s cooler. - Rest in the shade during the day. - Lie in depressions to conduct body heat into cooler ground. What is an earthworm's habitat? - Earthworms spend most of their time underground in burrows. How do earthworms move through their - They have long, slim, smooth bodies. - Tiny bristles (chaetae) on their undersides grip the sides of the burrow. burrows? What are producers? - Organisms that make their own food through photosynthesis or chemosynthesis. - Form the base of the food chain. Give examples of producers. - Plants: Grass, trees, algae. - Other producers: Phytoplankton, cyanobacteria. What are predators? - Animals that hunt, kill, and eat other animals (prey) for survival. Give examples of land predators. - Lion, wolf, hawk. Give examples of aquatic predators. - Shark, crocodile. What is prey? - Animals that are hunted and eaten by predators. - Often have adaptations like camouflage or speed to escape. Give examples of land prey. - Rabbit, zebra, antelope. Give examples of aquatic prey. - Small fish, shrimp. What are scavengers? - Animals that feed on dead animals or decaying organic matter. - Play an important role in cleaning the environment. Give examples of scavengers. - Vultures, hyenas, crabs. What are consumers? - Organisms that cannot make their own food and rely on eating other organisms. What are primary consumers? - Herbivores that eat producers. - Examples: Cows, deer. What are secondary consumers? - Small carnivores that eat primary consumers. - Example: Snakes. What are tertiary consumers? - Top predators that eat secondary consumers. - Example: Eagles. Who are ecologists? - Scientists who study organisms in their environment. What is ecology? - The study of organisms in their environment. How do ecologists study ecosystems? - They use sampling techniques to gather data from a small, representative part of the area. What is a food web? - A model that shows how energy is transferred between organisms. Questions2 Page 17 What are food chains in a food web? - Many interconnecting food chains within a food web. What are decomposers? - Organisms that get energy from dead organisms or their waste products. What role do decomposers play in the - Break down dead materials and recycle nutrients back into the environment. ecosystem? What is hyphae in fungi? - Hyphae are tiny, thread-like structures that make up the fungus. How do hyphae help the fungus survive? - Produce enzymes that digest starch and proteins in bread. - The small molecules diffuse into the hyphae for energy or cell growth. Questions2 Page 18