Grade 9 Biology: Meiosis, Mitosis, Reproduction

• This text concerns Biology for Grade 09 Advanced students, focusing on Term 2 Informal Practice Questions (IPQs)

Haploid vs Diploid Cells

• The eye cells of a female monkey have 60 chromosomes; gamete cells have 30 chromosomes
• Sperm cells of a male deer have 15 chromosomes; skin cells have 30 chromosomes
• Eye and skin cells are diploid, while sperm and gamete cells are haploid

Meiosis

• A diagram shows Metaphase I of meiosis

Meiosis Stages Diagrams

• Cytokinesis involves cell division, depicted by two separate cells
• Anaphase I shows chromosomes moving to opposite poles
• Metaphase I displays chromosomes aligned in the middle

Genetic Variation

• Crossing over during meiosis is a process that contributes to genetic variation

Mitosis vs Meiosis

• Meiosis produces four cells; mitosis produces two cells
• Meiosis has two divisions; mitosis has one
• Meiosis results in haploid cells; mitosis results in diploid cells

Sexual vs Asexual Reproduction

• Sexual reproduction requires two parent cells; asexual needs one
• Offspring from sexual reproduction are genetically different; asexual offspring are identical
• Animals reproduce sexually; bacteria reproduce asexually

Telomeres

• Telomeres are not found in the center of chromosomes
• Telomeres serve a protective function for chromosomes, and might be involved in aging and cancer

Genetic Disorders

• A karyotype shows Down's syndrome

Meiosis Errors

• Nondisjunction is a meiotic error where sister chromatids fail to separate

Plant Tissues

• Ground tissue stores material
• Trichomes offer protection to the plant

Stomata

• Stomata allow carbon dioxide into the plant and oxygen out during photosynthesis

Root Types

• Roots can be fibrous or taproot, or adventitious

Leaf Types

• Leaves can be simple and compound

Tropisms

• Phototropism is growth in response to light
• Gravitropism is growth in response to gravity
• Thigmotropism is growth in response to touch

Vegetative Reproduction

• Advantages include faster growth, more uniformity, and survival in stable environments

Flower Anatomy

• Pistil is the female reproductive organ
• Stamen is the male reproductive organ
• Petals attract pollinators
• Sepals protect the flower bud

Seed Development

• The ovary wall of a flower develops into the fruit in angiosperms
• The ovule develops into the seed

Seed Dispersal

• Hooks help seeds stick to animal fur
• Wings aid in seed dispersal by wind
• Low density helps seeds disperse in water

Animal Characteristics

• Animals are multicellular and have cells without cell walls
• Animal cells are heterotrophs

Asexual Reproduction in Animals

• A new organism regrowing from a lost body part is regeneration
• Eggs developing without fertilization is parthenogenesis
• Offspring develops as a growth on the parent is budding
• The parent breaks into pieces, and each piece developing into an adult animal is fragmentation

Animal Development

• Stages of animal development are fertilization, 2-cell stage, 16-cell stage, blastula, and gastrula
• The ectoderm becomes nervous tissue and skin
• The mesoderm becomes muscle tissue, circulatory, excretory, and respiratory systems
• The endoderm becomes digestive organs and digestive tract lining

Animal Behavior

• Behavior is a response to a stimulus
• Innate behaviors are genetically based, not linked to past experiences
• A newly hatched bird opening its mouth for food is an example of innate behavior

Different Types of Animal Behavior

• Learned behavior results from interaction between innate behaviors and past experiences
• Chimpanzees using rocks as tools is a learned behavior
• Fixed Action Pattern, is an innate behavior in a specific sequence, like a fixed action action in response to stimuli
• Habituation decreases response after repeated exposure to a stimulus without positive or negative effects
• Classical Conditioning occurs when an association is made between different stimuli; for example, a dog associated with food with the ringing of a bell
• Operant Conditioning is when an animal associates a response with a reward or punishment; For example, a rat finding a lever that provides food
• Imprinting is learning within a specific time period; example, is animals forming a social connection with the first object it sees after birth
• Thinking, reasoning, and processing information is cognitive behavior
• Long distances seasonal movements is migratory behavior
• Parents providing care to their offspring is nurturing behavior
• Finding and eating food is foraging behavior

Ecological Behavior

• Foraging behavior helps in finding and eating food for the survival of species

Skin Structure

• Number 2 in the diagram represents the dermis
• Number 3 in the diagram represents the subcutaneous layer

Integumentary System

• Functions of the integumentary system include sensory reception, vitamin production, and temperature regulation, via the skin
• The skin contributes to Vitamin D production

Skeleton

• The skull is part of the axial skeleton

Appendicular Skeleton

• Number 4 in the diagram represents a part of the appendicular skeleton

Bone Structure

• Spongy bone is represented by number 1
• Compact bone is represented by number 2

Joint Types

• A gliding joint is in the wrist
• A hinge joint is in the elbow
• A gliding joint allows side-to-side and back-and-forth movement